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Income and Adjunctive Eligibility of
Infants and Children
Individuals who meet WIC's categorical eligibility criteria must also
meet the program's income eligibility rules. WIC requires that the
applicant's income does not exceed 185 percent of the federal government's
poverty guidelines for the number of the individuals who are in the
applicant's family. However, individuals may also gain eligibility if they are
enrolled in any of the following means-tested transfer programs (adjunctive
eligibility): Temporary Assistance for Needy Families (TANF), food stamps,
or Medicaid. This chapter and the next examine alternative estimates of the
number of individuals who are categorically eligible for the program and
are eligible either on the basis of their income or through their enrollment
in a means-tested program.
Currently, USDA estimates the number of infants and children who
are income and adjunctively eligible by computing the number who live in
families whose annual income is less than or equal to 185 percent of the
family's poverty guideline amount. The panel, in its Phase I report (Na-
tional Research Council, 2001), concluded that the use of annual income
in lieu of a shorter time period for measuring income (e.g., over a month),
combined with the failure to fully account for adjunctive eligibility results
in a serious understatement of the numbers of infants and children who are
potentially eligible for WIC. This finding was based on the analysis of the
March 1999 Current Population Survey (CPS) file, which had been modi-
fied by the Urban Institute's Transfer Income Microsimulation 3 (TRIM)
model. In particular, the TRIM model imputed monthly income and, based
50
OCR for page 51
INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 51
on the reported participation in Medicaid and other income transfer pro-
grams, imputed enrollment in these programs to match enrollment levels
found in administrative data.
While the CPS-based TRIM data provide one important source of
information to judge the accuracy of USDA's current methodology, the
Survey of Income and Program Participation (SIPP) is another valuable
source of information. SIPP collects monthly income information from
respondents, so there is no need to impute them as there is with the CPS.
These monthly income reports would more accurately reflect the extent of
variability of income over the course of the year than the TRIM-imputed
income amounts. In the next two chapters, we examine the impact of in-
come variability and adjunctive eligibility on estimates of eligibility by ex-
amining data from SIPP in comparison to the CPS. In Appendix C we
attempt to reconcile the differences between the estimates of income vari-
ability and adjunctive eligibility from the CPS, TRIM, and SIPP.
The first section of this chapter reviews the WIC program rules per-
taining to income and adjunctive eligibility. This review shows that the
program does not contain a single precise definition of the time period over
which an applicant's income should be considered in assessing eligibility.
This flexibility in program rules implies that determination of an
individual's eligibility will depend on a judgment as to whether a pay pe-
riod, a week, a month, or a year is the appropriate time period to employ to
assess an individual's income eligibility. Given this local flexibility, it is not
clear what time period should be used to measure income in order to esti-
mate eligibility. An annual income measure is currently used, but there are
monthly income alternatives. The final section of the chapter examines the
impact of using monthly income instead of annual income and allowing
for eligibility through other means-tested programs.
INCOME AND ADJUNCTIVE ELIGIBILITY RULES
In determining income eligibility for WIC, there are three important
concepts: the economic unit, the definition of income, and the time period
for which the income is to be considered. WIC policy is to define the
economic unit in the following manner:
It is reasonable to assume that persons (other than those living in institu-
tional settings and homeless facilities) living in the residences of others,
whether related or not, are likely to be receiving support and some commin-
gling of resources which renders them members of the economic unit with
OCR for page 52
52 ESTIMATING ELIGIBILII~YANDPARTICIPATIONFOR THE WICPROGRAM
which they live. However, it is possible to establish that more than one eco-
nomic unit lives under one roof through appropriate questioning, which helps
to make a reasonable determination that there is general economic indepen-
dence of the units, i.e., that financial resources and support are retained inde-
pendently. For example, a pregnant woman who is sharing an apartment with
her sister may be determined to be a separate economic unit from her sister if
the certifier can reasonably establish that she has a source of income and is
paying her proportionate share of household, living and personal expenses
(Final WIC Policy Memorandum 99-4:8~.
Income is defined to be the gross cash income before deductions for in-
come taxes, employees' social security taxes, insurance premiums, bonds,
etc. Income includes the following items:
1. Monetary compensation for services, including wages, salary, com-
missions, and fees.
2. Net income from farm and nonfarm self-employment.
3. Social security benefits.
4. Dividends or interest on savings or bonds, income from estates or
trusts, and net rental income.
5. Public assistance and welfare payments.
6. Unemployment compensation.
7. Government civilian employee and military retirement or pen-
. ,
sloes or veterans payments.
8. Private pensions and annuities.
9. Alimony and child support payments.
10. Regular contributions from persons not living in the household.
11 . Net royalties.
12. Other cash income.
Other cash income includes but is not limited to cash amounts received or
withdrawn from any source, including savings, investments, trust accounts,
and other resources that are readily available to the family.
If a state agency chooses to use income guidelines identical to those
used for state or local free or reduced-price health care, it may also wish to
use the corresponding health care definition of income. However, when
applying the free or reduced-price health care definition of income, the
following exclusions must continue to be considered:
~ . The value of in-kind housing or other in-kind benefits.
OCR for page 53
INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 53
2. Payments or benefits provided under certain federal programs as
specified by law.
In addition, no expenses due to hardship or other deductions are allowed
unless the state agency can demonstrate that a household's gross income
before the deductions does not exceed the limit for reduced-price school
meals. The definition of income for WIC purposes, as established by the
National School Lunch Program, includes gross cash income earned by any
and all members of a family. Cash income also includes student financial
assistance, such as grants and scholarships, except those grants and scholar-
ships excluded as income, as set forth in Section 246.7 (21 (iv) ofthe regula-
tions, such as Pell Grants, State Student Incentive Grants, and National
Direct Student Loans (Food and Nutrition Service Instruction Memo 803-
31.
USDA provides the following instructions to state and local WIC agen-
cies with regard to the time period for which income should be considered
when determining income eligibility.
In determining the income eligibility of an applicant, the State agency may
instruct local agencies to consider the income of the family during the past
12 months and the family's current rate of income to determine which indi-
cator more accurately reflects the family's status. However, persons from fami-
lies with adult members who are unemployed shall be eligible based on in-
come during the period of unemployment if the loss of income causes the
current rate of income to be less than the State or local agency's income
guidelines for Program eligibility. State agencies have, and should exercise,
flexibility in deciding whether to use an applicant's current or annual rate of
income. For example, the family of a striker may have a lower income during
the period of a strike (depending on the union benefits and other sources of
income), but have an annual income which would exceed the WIC limit. In
this case, the use of current income (while on strike) may be more appropri-
ate. However, in the case of families of self-employed persons, including farm-
ers or seasonally employed persons whose income fluctuates, annual income
may be the more appropriate indicator of the need for WIC benefits. Other
examples in which the use of annual income is more appropriate include: (1)
a family member who is on a temporary leave of absence from employment,
such as maternity leave or to take an extended vacation; (2) teachers who are
paid on a 10-month basis and are temporarily on leave during the summer
months; and (3) college students who work only during the summer months
and/or their school breaks (Food and Nutrition Service Instruction Memo
803-3:5~.
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54 ESTIMATING ELIGIBILI~YANDPARTICIPATIONFOR THE WICPROGRAM
The Panel's Definitions
While the regulation appears to be quite specific in its intent to limit
WIC eligibility to those individuals with low to moderate incomes, a high
level of discretion is left to the local level in implementing these regula-
tions. While flexibility and discretion in the program may be desirable, a
lack of uniformity and specificity in the eligibility rules creates complexity
and uncertainty in estimating the number of individuals who are eligible.
In the absence of specific information on the implementation of WIC
income regulations across localities and by WIC staff, we use the following
definitions to represent the intent of the WIC regulations:
Economic Unit: All individuals who are related by blood or marriage
and reside in the same household. This is what is known as the census
definition of a family.
Income: All forms of income received in the form of cash, which in-
clude but are not limited to wages, salaries, self-employment income, rents,
dividends, unemployment and disability insurance, and the receipt of
Supplemental Security Income and TAN F. This concept of income is
known as census family money income.
Time Period: The previous month will be designated as the appropriate
time period for determining both the size of the economic unit and the
income to be considered.
Although these definitions are certainly not used uniformly in the field to
determine eligibility for WIC, we use these assumptions here because they
can be operationalized in the major data sets used to estimate eligibility and
participation and because they closely match the wording of the legisla-
tion. 1
In this chapter, we estimate the effect of using monthly data instead of
annual data, accounting for adjunctive eligibility and accounting for certi-
fication periods.2 One might believe that, armed with all the relevant infor-
1Differences in how localities implement regulations could cause errors in the estimates
presented in this report, as the estimates are made using a single method to account for
income and the economic unit, while local practice may vary from that. Such variation
increases the uncertainty level in the estimates, but there is no a priori reason to believe there
would be a systematic bias in the estimates.
20nce an infant is found to be income eligible, he or she is certified to be eligible for up
to one year. Children and pregnant and postpartum women are certified as eligible for 6-
month periods.
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INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 55
mation on a WIC applicant, it would be possible to determine whether an
individual is eligible for WIC or not. However, the language of the
program's eligibility rules and regulations does not lead to strict determina-
tion of who is eligible and who is not. Consider the following extreme
example. A mother with a child who is 2 years old has annual income that
exceeds 185 percent of the poverty guideline. However, in May, she loses
her job and her income falls below 185 percent of poverty. In rune, she
finds a new job and her income again exceeds the WIC income limits. In
this case, would the 2-year-old child be eligible for WIC and, if so, for how
many months? If the mother goes to the WIC office in May, her child will
meet the WIC income eligibility limits and will be certified to receive ben-
efits for 6 months. WIC regulations 246.7(i)~10) state that a participant
may not withhold or conceal information to obtain benefits. One interpre-
tation of this regulation is that, in rune, the mother is obligated to report to
the WIC offices that she has gained employment and report her income.
This interpretation implies that the child would have had only one month
of eligibility. However, based on correspondence from Food and Nutrition
Service (FNS) officials, it is WIC policy to apply the regulation only when
the mother is applying for benefits. The mother has no subsequent obliga-
tion to reveal that her family's income has changed. When the mother reap-
plies for benefits in November, the child would not be recertified if the
mother's income continued to exceed 185 percent of poverty. This inter-
pretation implies that if the WIC offices do not discover that the mother is
employed, the child has 6 months of eligibility.
In the panel's Phase I report, the effect of different definitions of the
economic unit was estimated and found to have a small impact on the
numbers estimated to be eligible (National Research Council, 20011. Use
of a restrictive definition of the economic unit (one that would tend to
make the family ineligible for WIC) decreased eligibility estimates for in-
fants by 0.2 percent and for children by 0.3 percent. Use of a generous
definition of the economic unit (one that would tend to make the
family eligible for WIC) increased the number of infants estimated to be
eligible by 1 percent and increased the number of children estimated to
be eligible by 1.5 percent.
Relevance for Estimating the Number of Income-Elitrible Individuals
v
USDA utilizes the March Income and Demographic Supplement to
the Current Population Survey to estimate the number of WIC income-
OCR for page 56
56 ESTIMATING ELIGIBILITYAND PAR TICIPATION FOR THE ~CPROGR~
eligible individuals. Since the CPS contains only annual income informa-
tion from respondents, USDA's estimates of the number of infants and
children who are both categorically eligible and income eligible are based
on the counts of individuals with annual census family money income less
than or equal to 185 percent of the poverty guidelines of the U.S. Depart-
ment of Health and Human Services (DHHS). USDA's methodology cur-
rently makes a very small adjustment to account for the possibility that
infants and children may also be adjunctively eligible through enrollment
in other means-tested programs.
While the CPS is the primary source of data used for the analysis of
many low-income programs, it is not an ideal data base for the estimation
ofthe number of WIC-eligible individuals. The CPS survey design requires
the household respondent to list the ages of all household members as of
March of the survey year; however, annual income information is collected
from the previous year. Ideally we would want to know the family structure
and membership during the previous year the year for which annual in-
come is measured. Given that family structure is not static, especially in the
low-income population, the number of family members in the previous
year could be quite different from what it is in March of the following year.
For example, consider a child who is born in February of the survey year. In
this case, the income from the previous year does not refer to the income
available to the infant at the time of WIC application, but the income that
would have been considered when the mother applied as a pregnant woman.
Moreover, the snapshot of the family provided by the CPS is not a true
picture of how family membership and hence eligibility can change over
the course of the year.
Variability of income over the course of the year has always been con-
sidered a serious source of bias in the estimates of the number of income-
eligible infants and children. For budgetary purposes, USDA is interested
in predicting the number of infants and children that will be eligible to
participate during the year. Given that the CPS does not collect monthly
family income information, USDA assumes that if the family's annual in-
come is less than or equal to 185 percent of federal poverty guidelines, the
infants and children in the family will be eligible for 12 months. Otherwise
they will have zero months of eligibility.
The use of annual income to determine income eligibility provides an
accurate determination of the number of months an infant or child is in-
come eligible only if the family's monthly income is constant over the year.
However, if monthly income does vary, then USDA's use of annual income
OCR for page 57
INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 57
could produce two potential errors. First, an error will occur if the
individual's annual family income is less than or equal to 185 percent ofthe
federal poverty guidelines, but for some months the individual has at least
one month in which her income is greater than the eligibility limit. In
other words, this individual would be ineligible for WIC in the months for
which income is above the eligibility cutoff. The second type of error will
occur for individuals whose average monthly income is greater than 185
percent of federal poverty guidelines but who have some months in which
their income is less than or equal to it. In these cases, the use of annual
income understates the number of months the individual would have been
income eligible. These two types of errors have opposite effects on the aver-
age number of months that family income is less than or equal to 185
percent of federal poverty guidelines. However, as we will see, once WIC
certification periods are considered (1 year for infants and 6 months for
every other categorical group), more people have annual incomes above but
at least one month of income below 185 percent of federal poverty guide-
lines.
Focusing on the average number of months that family income is suffi-
ciently low to qualify for WIC can be misleading. WIC does not require
individuals to be income eligible each month during their participation in
the program. Once an infant is found to be eligible, the infant is certified
for 12 months of eligibility, or until the first birthday. Children must be
certified as income eligible every 6 months. This certification process will
tend to dampen the impact of errors created because individuals have an-
nual income less than or equal to 185 percent of federal poverty guidelines
but monthly income that is not consistently below the income threshold.
Certification, however, will increase the significance of the errors produced,
because individuals have annual income greater than 185 percent of pov-
erty but dips in monthly income below the eligibility threshold. The com-
bination of the use of annual income and ignoring the certification process
may significantly understate the average number of infants and children
who are income eligible at the time of application.
A final area of concern pertains to the inadequate method currently
used to account for adjunctive eligibility through enrollment in the other
means-tested programs, especially Medicaid. In an effort to ensure the
health coverage of infants and young children, over the past decade the
Congress and state governments have increased the income limits for eligi-
bility in the Medicaid program. Many states have income limits for infants
and children that exceed 185 percent of the federal poverty guidelines (see
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58 ESTIMATING ELIGIBILI~YANDPARTICIPATIONFOR THE WICPROGRAM
National Governors Association, 20031. Even in states with Medicaid in-
come limits at or below 185 percent of poverty guidelines, differences in
how the two programs define income mean that individuals whose income
as calculated by WIC was greater than 185 percent of poverty might be
income eligible for Medicaid and thus adjunctively eligible for WIC. The
Medicaid program uses a net measure of income, allowing various deduc-
tions in income. WIC allows no deductions. Hence, estimates of the eli-
gible population need to account for adjunctive eligibility.
The preceding information describes reasons that the current methods
understate the number of individuals who are eligible for WIC. While
USDA could easily modify its methodology to account for adjunctive eligi-
bility by using participation in means-tested programs reported by the sur-
vey respondent, the impact of monthly income cannot be simply intro-
duced into estimates that rely on annual income reports from the CPS. In
the next section, we use SIPP to examine the consequences of relying on
annual income and the failure to fully account for adjunctive eligibility.
IMPACT OF MONTHLY INCOME
AND ADJUNCTIVE ELIGIBILITY
Using SIPP data
Gordon et al. (1997) undertook the first comprehensive examination
of the impact of monthly income on the estimates of the number of in-
come-eligible infants and children.3 Utilizing SIPP data from the 1990 and
1991 full panel files, the authors constructed a pooled extract covering
calendar years 1990 through 1992. Table 5- 1 (first column) summarizes
this study's results.
Employing the USDA methodology with the March CPS public use
files, Gordon et al. (1997) estimated that 42.6 percent of all infants and
42.5 percent of children would have been income eligible during the pe-
riod 1990 to 1992. When they utilized SIPP monthly income data to con-
struct an annual measure of income to mirror the CPS annual data, Gor-
don et al. estimated that a slightly smaller percentage of infants (41.7
percent) and children (41.8 percent) would have been income eligible.
3Heiser and Doyle (1990) and Doyle (1990) examined the question of monthly versus
annual income; however, both studies employed only one month of SIPP data.
OCR for page 59
INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 59
TABLE 5-1 Estimates of Income Eligibility Based on Monthly Versus
Annual Income (Percentage of All Individuals), 1990-1992, 1997, and
1998
1990-2 (Pooled Dataja 19976 19986
Infants
CPS
Annual 42.6 39.7 39.2
SIPP
Annual 41.7 38.9 35.1
Average monthly 43.8 43.5 41.3
Eligible in any month 52.1 58.9 57.5
Certification periods 56.6 54.1
Children
CPS
Annual 42.5 41.1 40.4
SIPP
Annual 41.8 42.4 39.6
Average monthly 41.5 44.8 42.1
Eligible in any month 52.8 62.0 59.4
Certification periods 56.8 53.9
aGordon et al. (1997:Table III.1~.
The CPS estimates are from panel calculations based on extracts from the Urban Insti-
tute TRIM files for the respective calendar years. The SIPP estimates are from calcula-
tions made by Bitler et al. (2002~.
These results provide some evidence that the annualized SIPP data closely
replicate the estimates found in the March CPS.
Gordon et al. (1997) then utilized the monthly data from SIPP by first
computing the number of months that infants and children would have
been income eligible (labeled "average monthly" in the table). They esti-
mated that infants would be found eligible 43.8 percent of the total pos-
sible number of months that they were categorically eligible as infants. The
corresponding estimate for children was 41.5 percent. These average
monthly estimates were only 5 percent higher for infants and 1 percent
lower for children than the SIPP annual estimates. In neither case were the
differences statistically different.
The average number of months that an infant or child would have
OCR for page 60
60 ESTIMATING ELIGIBILITYAND PAR TICIPATION FOR THE ~CPROGR~
been income eligible reflects the situation in which WIC staff recertify in-
dividuals on a monthly basis. This does not reflect actual WIC regulations
or practice. As we noted above, it is unclear whether the resulting eligibility
estimates based on this certification process will differ greatly from esti-
mates based on the use of annual income. To provide an upper-bound
estimate of the effect of the use of monthly income, Gordon et al. (1997)
estimated the percentage of infants and children that had at least one month
of income eligibility. This estimate is intended to reflect a certification pro-
cess in which individuals are given 12 months of eligibility if their worst
month during the year is less than 185 percent of federal poverty guide-
lines. Gordon et al. found that when this upper bound certification proce-
dure was employed, there was a significant increase in the number of in-
fants (52 percent of all infants, or 25 percent more than when annual
income is employed) and children (53 percent of all children, or 26 percent
more than when annual income is employed).
The Gordon et al. (1997) study suggests that not using monthly in-
come nor accounting for the WIC certification process is an important
shortcoming of the USDA methodology. However, because the study uses
older data and did not simulate realistic WIC certification periods, two
members of the panel undertook an similar analysis using data from the
1996 SIPP panel.4 Table 5-1 (second and third columns) presents estimates
from the 1996 SIPP panel for calendar years 1997 and 1998.
When SIPP data were used to create annual measures of income and
family structure for these same years, a smaller proportion of infants was
found to be income eligible than implied by the CPS a result that is
consistent with the Gordon et al. (1997) study. The results are somewhat
mixed for children. In 1997, the annualized SIPP shows a slight increase in
the proportion of income-eligible children compared with the CPS, while
in 1998 the proportion is lower. These differences are minor, however, so
we conclude that the proportion of infants and children who are income
eligible based on annual income is roughly equal from the March CPS and
from the annualized SIPP data.
The use of monthly certification periods (average monthly) continues
to create a small increase in the number of income-eligible children (6
percent increase in both 1997 and 1998) but a larger impact on infants (12
4Panel members Janet Currie and John Karl Scholz as a part of a larger research project
provided the estimates reported in this chapter (see Bitter et al., 2002).
OCR for page 61
INCOME AND ADJUNCTI~ELIGIBILIKOFINFANTS AND CHIDDEN 61
and 17 percent increases). Using the eligible-in-any-month measure dra-
matically increases eligibility estimates. Compared with the use of annual
income, the SIPP data indicate that there would be between 52 and 64
percent more income-eligible infants in 1997 and 1998, respectively. The
estimates for children are equally large 46 and 50 percent in the two
years. These estimates of eligibility appear to become significantly larger
over the decade of the 1990s. The proportion of infants who were income
eligible rose from 52 percent in the early 1990s to roughly 59 percent in
1997. The proportion of children rose even faster, from 53 to 62 percent in
the same period.
Unlike the CPS data, the SIPP panel data permit a more accurate rep-
resentation of the WIC certification process. When this process is consid-
ered (e.g., if the monthly family income for a child is below the income
eligibility threshold, the child is considered eligible for the next 6 months;
for infants, someone who becomes eligible in a month is then considered
eligible for the next 12 months or until the end of the calendar year for
which the estimates are being made), combined with the use of SIPP
monthly income, there remains a significant and large increase in the num-
ber of months that infants and children are income eligible compared with
the situation when annual income is used. In 1997 and 1998, there are 46
and 54 percent more infants and 34 and 36 percent more children who are
income eligible for WIC.
These calculations from the 1996 SIPP panel indicate that the impact
of monthly income is significantly different from what was found in the
earlier Gordon et al. study (19971. Given that the SIPP data are reported
and are not the result of imputations, we conclude that the impact of the
use of monthly income with certification periods is larger than previous
estimations indicated. Compared with the use of annual income, 50 per-
cent more infants and 35 percent more children may be income eligible for
WIC when monthly income and certification periods are considered.
Combined Impact of Monthly Income, Adjunctive Eligibility, and
Certification Periods
The current USDA methodology makes only a minor adjustment to
account for infants and children who gain WIC eligibility by their enroll-
ment in TANF, food stamps, or Medicaid. It makes no adjustment for
women who gain adjunctive eligibility. Table 5-2 shows the impact of in-
cluding all those who report participation in other means-tested programs
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62 ESTIMATING ELIGIBILI>~D PAR TICIPATION FOR THE ~CPROG~
TABLE 5-2 Percentage of Infants and Children Who Are Income
Eligible and Adjunctively Eligible
Calendar Year
1997
Calendar Year
1998
Infants
CPS
Annual income
Annual income and adjunctive eligibility
SIPP
Annual income
Monthly income
Monthly income and adjunctive eligibility
Children
CPS
Annual
Annual income and adjunctive eligibility
SIPP
Annual income
Monthly income
Monthly income and adjunctive eligibility
39.7
46.7
38.9
56.6
60.0
41.1
45.2
42.4
56.8
59.0
39.2
46.7
35.1
54.1
58.1
40.4
46.0
39.6
53.9
56.7
aPersons who report participation in TANF, food stamps, or Medicaid are included as
adjunctively eligible for WIC regardless of their incomes.
on CPS-based estimates of eligibility (using the annual measure of income).
Estimates for both infants and children are presented. The impact of this
simple alteration in the USDA methodology has a substantial impact on
the estimate of the number of eligible infants and children in 1997 and
1998. The proportion of eligible infants is estimated to increase from 39.7
to 46.7 percent, or by 18 percent; a similar increase is found in 1998. The
proportion of children increases from 41.1 to 45.2 percent in 1997, which
is a 10 percent increase; a slightly larger increase is found in 1998.
This comparison suggests that failing to consider adjunctive eligibility
serves to understate the number of infants and children eligible for WIC,
and the magnitude of these numbers may be overstated because some of
these people may also qualify if a monthly income measure is used. Indi-
viduals who participate in these means-tested programs can have moderate
income when considered on an annual basis, but they are most likely to
have low incomes for several months during the year. Hence, including
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INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 63
those who report participation in these means-tested programs will include
some individuals who have monthly incomes that would have qualified
them for WIC although their annual income exceeded the WIC income
limits. To more accurately reflect the marginal effect of adjunctive eligibil-
ity, we employed the SIPP data. The results of these calculations appear in
Table 5-2.
As we have already observed, the use of monthly income and certifica-
tion periods has a significant and substantial impact on the estimates of the
number of income-eligible infants and children. Estimates of income-eli-
gible infants increased by 46 and 54 percent in 1997 and 1998, respec-
tively. The number of income-eligible children rises 34 and 36 percent.
The marginal impact of using the SIPP-reported enrollment in TAN F. food
stamps, and Medicaid to simulate adjunctive eligibility is smaller in com-
parison to the impact of monthly income and is smaller in comparison
with the impact that was found in the CPS. Compared with the estimates
that incorporate monthly income and certification periods, adjunctive eli-
gibility increases the estimates of the number of WIC-eligible infants by
roughly 6 percent, while estimates of income-eligible children are increased
by 5 percent. To the extent that comparisons between the CPS and SIPP
can be made, these estimates suggest that a significant proportion of the
impact of adjunctive eligibility found in the CPS reflected eligibility that
also could be gained through consideration of low monthly income.
The relatively small impact of considering adjunctive eligibility found
in SIPP as well as in the CPS could be the result of the underreporting of
participation in TANF and food stamps. But underreporting of these pro-
grams is a less serious problem for estimating WIC eligibility, because the
income eligibility limits of these programs are considerably below the in-
come eligibility limit of the WIC program, and thus few people will gain
eligibility for WIC through participation in TANF or food stamps alone.
Underreporting of participation in Medicaid is potentially a much more
serious problem, because the income eligibility limits of Medicaid are, in
most states, equal to or above the WIC eligibility limits. Thus, there is
potential for a greater number of people to gain eligibility for WIC solely
through enrollment in Medicaid.
Some studies have attempted to gauge the extent of underreporting of
Medicaid in the CPS and SIPP, but mixed results have been found, and
none of the results pertains exactly to the WIC-eligible population of in-
fants and children under the age of 5, pregnant women, and women less
than 12 months postpartum. Wheaton and Giannarelli (2000) found that
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64 ESTIMATING ELIGIBILITYAND PAR TICIPATION FOR THE ~CPROGR~
the percentage of households (with a noninstitutionalized head) reporting
Medicaid participation in the March CPS accounted for only 68 percent of
the Medicaid caseload in 1998. In a slightly different comparison of the
number of survey-reported Medicaid recipients under age 65 (which again,
does not exactly match the WIC-eligible population) to the number of
recipients reported in the Medicaid administrative files under age 65, Bitter
et al. (2002) found overreporting of Medicaid receipt in 1997 in both the
March CPS and SIPP. The ratio of reported recipients to administrative
totals was 112.8 percent in the March CPS, and 117.9 percent in SIPP.
However, the 1998 ratios show sizable underreporting of WIC participa-
tion in the March CPS (87.3 percent) and a slight underreporting in SIPP
(95.7 percent).5 In a study that linked individual Medicaid records in Cali-
fornia to individual SIPP survey responses of Medicaid enrollment for re-
spondents from California, Card et al. (2001) found that SIPP underesti-
mates the California Medicaid enrollment totals by about 10 percent. This
study also found that some respondents who reported Medicaid enroll-
ment were not identified as actual Medicaid enrollees by the administrative
data. Such false positive reports for low-income children were not small,
either (possibly up to 20 percent for poor children in California).
It is difficult to gauge the exact magnitude of this problem, however,
because the administrative data from the Medicaid program are not re-
ported specifically for the age group of infants and children under age 5. In
comparing SIPP reports to CPS reports, it appears that SIPP data have a
higher proportion of infants and roughly an equivalent proportion of chil-
dren reporting Medicaid participation. In 1997, 26.2 percent of infants
and 20.6 percent of children reported Medicaid participation. In the same
year, the CPS indicates that 24.7 percent of infants and 21.2 percent of
children participated in Medicaid. In 1998, the proportions were similar.
The SIPP data reports that 24.9 percent of infants and 19.5 percent of
children were in the Medicaid program, while the proportions from the
CPS are 22.9 percent and 19.2 percent, respectively.
5Bitler et al. (2002) used the Medicaid recipiency report for each member of the house-
hold, summed these for the household, and weighted them by the household-supplement
weight, which may explain the difference in their results compared with the Wheaton and
Giannarelli (2000) results.
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INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 65
Ceri'ficai'on Periods and Elig~bilit~r
Accounting for monthly income, certification periods, and adjunctive
eligibility has a large impact on the estimated number of eligible persons.
This might raise concerns that the 6-, 9-, and 12-month certification peri-
ods allow some people who gain eligibility for WIC due to one or two
months of low income or means tested program participation to continue
to be certified for WIC for months in which they are not income or
adjunctively eligible. Table 5-3 attempts to explain how prevalent such
people might be. The 1997 SIPP data are used to split the estimates of
eligible infants and children into one of three categories: (1) those whose
months of eligibility exactly equal the number of months for which they
would be certified as eligible (e.g. they are eligible each month after the
month in which they were initially certified as eligible); (2) those whose
numbers of months of eligibility are less than the number of months they
would be certified as eligible but who have annual incomes below 185
percent of poverty or who report participation in means tested programs
TABLE 5-3 Percentage Distribution of the Number of Months of
Simulated Certification by Simulated Months and Type of Eligibility for
Infants and Children in 1997
Distribution of Simulated
Months of Certification
Simulated Months and Type of Eligibility Infants Children Total
Every montha 67.8 74.3 72.8
Not every month but simulated eligibility
based on annual or adjunctive~ 14] 11.2 11.8
Not every month but at least one month
oflowincomec 18.1 14.5 15.3
aNumber of months of simulated eligibility exactly equals number of months of simu-
lated certification.
Number of months of simulated eligibility less than number of months of simulated
certification, but annual income is less than 185 percent of poverty or adjunctively
eligible.
Number of months of simulated eligibility less than number of months of simulated
certification, annual income greater than 185 percent of poverty, not adjunctively eli-
gible, but had at least one month of income below 185 percent of poverty.
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66 ESTI~TING ELIGIBILI>~D PAR TICIPATION FOR THE ~CPROG~
and are adjunctively eligible; and (3) those whose number of months of
eligibility are less than the number of months they would be certified and
have annual income above 185 percent of poverty and are not adjunctively
eligible. It is this last group that is of most concern because presumably
they only have a few months where their incomes dip below the eligibility
threshold, yet they could be certified for receipt of WIC for more months.
Table 5-3 shows the distribution of the number of months of certification
to these three types of eligible infants and children.6
The last row in Table 5-3 shows the number of case months during
1997 that fall into the third category that is, months in which an infant
or child was certified as eligible but not eligible that month based on that
month's income, nor annual income or adjunctive eligibility. Ofthe months
that were certified to infants, 18 percent were to infants whose monthly
household income exceeded eligibility limits in one or more of the months
in which they were certified, whose annual household income exceeded
185 percent of poverty, and who did not report participation in programs
that confer adjunctive eligibility during the calendar year (the third group
from the above classification). And 14 percent of all the months certified
to children were to children with similar eligibility status.7
Although 18 and 14 percent of the certification months are not small
numbers, it is important to recognize that many of the individuals that
these months represent could have been eligible for 5 months of a 6-month
certification period, but would have one month included in the last cat-
egory. We calculated the average number of months of certification and the
6Note that censoring before 1997 means we do not observe the full income and certifi-
cation periods of all individuals. Table 5-3 includes those individuals who were certified in
1996 but have certification carry-over periods into 1997.
7We also examined the reported participation rates of those falling into the third cat-
egory of eligibility. Twenty-five percent of infants and 11 percent of children in this category
reported participation in WIC. These are low participation rates compared to those of all
eligible infants and children (see Chapter 8). However, these rates are not adjusted for
underreporting of WIC participation (as Chapter 8 estimates are) because we do not have
information to allocate aggregate levels of participation into the three types of eligibility
categories in Table 5-3. Those persons who have fewer months of income eligibility than they
would have been certified for (third category) have greater incomes and thus may have higher
rates of underreporting of WIC participation. This may be due to a greater perceived stigma
or because they do not recall short periods of participation (they may have picked up WIC
benefits only for the one or two months they had low income even though they were certified
for more months).
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INCOME AND ADJUNCTIVE ELIGIBILITY OFINFANTS AND CHILDREN 67
average number of months of eligibility of infants and children who fall in
this third category. We find that infants from this category received 5.8
months of certification on average but were eligible for 1.6 months on
average. Children received 4.5 months of certification for 1.9 months of
eligibility on average.
SUMMARY
Neither the CPS nor SIPP data are ideal for estimating the number of
WIC income- and adjunctively eligible infants and children. The SIPP data
provide a more reliable estimate of monthly income, which is demonstrated
by the large and significant effect of using monthly income for eligibility
estimates. The use of the SIPP data requires that reported enrollment in
means-tested programs must be employed to impute adjunctive eligibility.
There is some question about whether the reporting of participation in
these programs is accurate. Thus, some concern must be given to whether
total eligibility is understated. At this stage, the panel cannot assign too
much confidence to the point estimates. However, one conclusion is ines-
capable the use of the public use CPS files significantly understates the
proportion of infants and children who are eligible for WIC on the basis of
monthly income. Instead of roughly 40 percent eligibility of all infants and
children, the true percentage of all infants and children who are WIC eli-
gible may be as high as 54 percent.
CONCLUSION: The current method used to estimate income eligi-
bility for infants and children significantly understates the numbers
eligible because income variation over time and adjunctive eligibility
are not adequately measured.
The essence of this conclusion is that our estimates show that more
people are eligible for the program when monthly income and adjunctive
eligibility are considered in the estimation methodology. It does not neces-
sarily imply that these additional eligible people will participate in WIC.
Those who gain eligibility through Medicaid participation or because they
have a few months of income below 185 percent of poverty are likely to
have higher incomes than other eligible people. These higher income groups
may find the relatively small value of WIC food packages too small to
entice them to participate. The only claim of the conclusion is that current
methods used to estimate eligibility underestimate it.
Representative terms from entire chapter:
adjunctive eligibility
