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GAO-02-290R: 

United States General Accounting Office: 
Washington, DC 20548: 

December 14, 2001: 

The Honorable William J. Coyne: 
Ranking Minority Member: 
Subcommittee on Oversight: 
Committee on Ways and Means: 
House of Representatives: 

Subject: Earned Income Tax Credit Eligibility and Participation: 

Dear Mr. Coyne: 

The Earned Income Tax Credit (EIC), which is expected to provide over 
$30 billion in refundable credits in fiscal year 2002, is a major 
federal effort to assist the working poor. The EIC is intended to 
offset the burden of the Social Security payroll tax on low-income 
workers and to encourage low-income individuals to work. The amounts of 
credit that taxpayers receive depend on the taxpayers’ incomes and the 
number of qualifying children they have. [Footnote 1] Taxpayers must 
file a tax return in order to claim the credit. Prior evidence suggests 
that many eligible households have not received the credit. [Footnote 
2] You asked us to provide estimates of (1) the number of eligible 
households and the number of those who did and did not participate in 
the EIC program and (2) the amounts of credit foregone by 
nonparticipating households. You also asked that we provide these 
estimates disaggregated by the number of qualifying children in the
households claiming the credit. 

We used data from the Census Bureau’s Current Population Survey (CPS) 
for 1999 to estimate the number of households eligible for the EIC. We 
obtained estimates from the Internal Revenue Service (IRS) for the 
number of eligible taxpayers who claimed the EIC for tax year 1999. 
Because the CPS and IRS data are based on samples, our estimates are 
subject to sampling error. [Footnote 3] In addition, the CPS database, 
while useful for estimating EIC eligibility, do not contain all of the 
data needed to definitively determine EIC eligibility. Our methodology 
and its limitations are described in further detail in the enclosure. 
We sent a draft of this correspondence to IRS for review and comment. 
Their comments and our response are summarized at the end of this 
letter. We did our work between February and December 2001 in accordance
with generally accepted government auditing standards. 

Results: 

Table 1 shows the number of eligible households, [Footnote 4] the 
number of those households that did and did not participate in the EIC 
program, and the participation rate. Of the total of 17.2 million 
households that were eligible for the credit, about 12.9 million 
claimed the credit, representing a participation rate of about 75 
percent. The participation rate varied considerably by number of 
qualifying children in the household. The participation rates for 
households with one and two qualifying children were about 96 percent 
and 93 percent, respectively. In contrast, the participation rate for 
households with three or more qualifying children was about 62.5 
percent, and the rate for households with no qualifying children was 
only about 44.7 percent. 

The data available did not enable us to determine the reasons for these 
differences. The differences in participation rates may reflect actual 
behavioral differences across the household types, but they may also 
reflect limitations in the data. Both explanations are discussed in the 
enclosure. Given the possibility that limitations in our data may 
explain some of the variation in participation rates by number of 
qualifying children and the larger confidence intervals for these 
subgroups due to their smaller sample size, we believe the estimates 
for the subgroups in tables 1 and 2 are less certain than the estimates 
for all households. 

Table 1: Number of Eligible Households, by Participation Status and 
Number of Qualifying Children, 1999[A], (Dollars in millions): 

Total: 
Households, Total eligible: 17.2 +/- .4; 
Households, Eligible participants: 12.9 +/- .4;
Households, Eligible nonparticipants: 4.3 +/- .5
Participation rate: 75.0 +/ 2.7%. 

0 qualifying children: 
Households, Total eligible: 4.7 +/- .2; 
Households, Eligible participants: 2.1 +/- .2; 
Households, Eligible nonparticipants:2.6 +/- .3; 
Participation rate: 44.7 +/- 3.9%. 

1 qualifying child: 
Households, Total eligible: 5.0 +/- .2; 
Households, Eligible participants: 4.8 +/- .3; 
Households, Eligible nonparticipants: 0.2 +/- .4; 
Participation rate: 96.0 +/- 7.7%. 

2 qualifying children: 
Households, Total eligible: 4.3 +/- .2; 
Households, Eligible participants: 4.0 +/- .3; 
Households, Eligible nonparticipants: 0.3 +/- .4; 
Participation rate: 93.0 +/- 8.3%. 

3 or more qualifying children: 
Households, Total eligible: 3.2 +/- .2; 
Households, Eligible participants: 2.0 +/- .2; 
Households, Eligible nonparticipants: 1.2 +/- .3; 
Participation rate: 62.5 +/- 8.3%. 

[A] The actual number of households in any of the subgroups presented 
in the table cannot be less than zero and the actual participation 
rates cannot exceed 100 percent. 

Sources: GAO’s analysis of data from the CPS and IRS. 

[End of table] 

In total, about 4.3 million eligible households did not claim the 
credit. Figure 1 shows how these households were distributed by number 
of qualifying children. More than half (about 60 percent) of the 
eligible nonparticipating households had no qualifying children. Most 
of the remaining eligible nonparticipating households (about 28 percent 
of the total) had three or more qualifying children. Households with 
one or two qualifying children accounted for only about 12 percent of 
the nonparticipants, even though they represented about 54 percent of 
all eligible households. 

Figure 1: Eligible Nonparticipating Households, by Number of Qualifying 
Children, 1999: 

[See PDF for image] 

This figure is a pic-chart, depicting the following data: 

Eligible Nonparticipating Households, by Number of Qualifying Children, 
1999: 
No Child: 60%; 
One Child: 5%; 
Two Children: 7%; 
Three or More Children: 28%. 

Sources: GAO’s analysis of data from the CPS and IRS. 

[End of figure] 

We estimate that in 1999 all qualifying households were eligible to 
claim a total of $23.5 billion of EIC. IRS estimates that households 
that actually participated in the program were eligible to claim $20.9 
billion of EIC. This implies that nonparticipating households did not 
receive about $2.7 billion of credits for which they were eligible. The 
amount foregone by nonparticipating households represented about 11.1 
percent of the total credit that households were eligible to claim. 
Table 2 shows the amounts of EIC that nonparticipating households 
within each of the qualifying child categories were eligible to claim. 
The table compares these amounts to the total amounts of EIC that all 
households within those categories were eligible to claim. 

Table 2: Amounts of EIC That Participating and Nonparticipating 
Households Were Eligible to Claim, by Number of Qualifying Children, 
1999[A] (Dollars in billions): 

Total: 
Total amount that households were eligible to claim: $23.5 +/- .5; 
Amount that households who participated were eligible to claim: $20.9 
+/- .7; 
Amount that households who did not participate were eligible to claim: 
$2.7 +/- .7; 
Amount that nonparticipants were eligible to claim as a percent of the 
total amount that households were eligible to claim: 11.1 +/- 3.5%. 

0 qualifying children: 
Total amount that households were eligible to claim: $0.8 +/- .0; 
Amount that households who participated were eligible to claim: $.4 +/- 
.0; 
Amount that households who did not participate were eligible to claim: 
$0.4 +/- .0; 
Amount that nonparticipants were eligible to claim as a percent of the 
total amount that households were eligible to claim: $50.0 +/- 4.1%. 

1 qualifying child: 
Total amount that households were eligible to claim: $7.2 +/- .2; 
Amount that households who participated were eligible to claim: $7.1 
+/- .3; 
Amount that households who did not participate were eligible to claim: 
$0.1 +/- .3; 
Amount that nonparticipants were eligible to claim as a percent of the 
total amount that households were eligible to claim: $1.4 +/- 4.8%. 

2 qualifying children: 
Total amount that households were eligible to claim: $9.0 +/- .2; 
Amount that households who participated were eligible to claim: $9.0 
+/- .4; 
Amount that households who did not participate were eligible to claim: 
$0.0 +/- .5; 
Amount that nonparticipants were eligible to claim as a percent of the 
total amount that households were eligible to claim: 0.0 +/- 5.4%. 

3 or more qualifying children: 
Total amount that households were eligible to claim: $6.5 +/- .2; 
Amount that households who participated were eligible to claim: $4.3 
+/- .3; 
Amount that households who did not participate were eligible to claim: 
$2.2 +/- .4; 
Amount that nonparticipants were eligible to claim as a percent of the 
total amount that households were eligible to claim: $33.8 +/- 5.0%. 

[A] The actual number of households in any of the subgroups presented 
in the table cannot be less than zero. The same is true for the 
percentages in the last column. Numbers may not sum to totals due to 
rounding. 

Sources: GAO’s analysis of data from the CPS and IRS. 

[End of table] 

Figure 2 shows that households with three or more qualifying children 
accounted for the preponderance (about 81 percent) of the EIC that 
nonparticipating households were eligible to claim. Nonparticipating 
households with no eligible children accounted for most of the 
remainder (about 15 percent). 

Figure 2: Distribution of EIC That Nonparticipating Households Were 
Eligible to Claim, by Number of Qualifying Children in Household, 1999: 

[See PDF for image] 

This figure is a pie-chart, depicting the following data: 

Distribution of EIC That Nonparticipating Households Were Eligible to 
Claim, by Number of Qualifying Children in Household, 1999: 

No Child: 15%; 
One Child: 4%; 
Two Children: 0%; 
Three or More Children: 81%. 

Sources: GAO’s analysis of data from the CPS and IRS. 

[End of figure] 

Agency Comments and Our Evaluation: 

On December 12, 2001, we spoke with a representative of the Director of 
IRS’ Office of Research who provided oral comments on our draft letter. 
The Director suggested that we add a few more specific caveats to the 
ones that we already listed in our methodology discussion regarding the 
use of CPS data to determine the number of households eligible for the 
EITC. He also suggested that we describe in more detail how we applied 
the eligibility rules to CPS data and that we clarify certain statements
made in the draft. We modified the correspondence as appropriate. 

As arranged with your staff, unless you publicly announce its contents 
earlier, we plan no further distribution of this report until 30 days 
after the date of this letter. At that time, we will send copies to the 
Secretary of the Treasury, the Commissioner of Internal Revenue, and 
the Chairmen and Ranking Minority Members of the Senate Finance 
Committee and the House Ways and Means Committee, as well as the 
Chairman of the latter Committee’s Oversight Subcommittee. The letter 
will also be available on GAO’s home page at [hyperlink, 
http://www.gao.gov]. 

If you have any questions, you may contact Jim Wozny or me at (202) 512-
9110. Kevin Daly, Wendy Ahmed, and MacDonald Phillips made key 
contributions to this letter. 

Sincerely yours, 

Signed by: 

James R. White: 
Director, Tax Issues: 

[End of correspondence] 

Enclosure: 

Methodology for Estimating Participation Rates for the Earned Income 
Tax Credit: 

We estimated the number of eligible households (individuals and married 
couples) using the eligibility rules under section 32 of the Internal 
Revenue Code and data from the Census Bureau’s Current Population 
Survey (CPS). The CPS is a sample of households with information about 
their income, age, marital status, number of children, and other 
characteristics. We analyzed the data reported in the 2000 March 
Supplement of CPS which contains this information for the preceding 
year. We identified households in the CPS that met the eligibility 
rules under the Internal Revenue Code, and, using the CPS sample 
weights, estimated the number of eligible households in the U.S. 
population. We also estimated the amount of credit that these 
households were eligible to claim. 

We obtained estimates of the number of eligible claimants and the 
amount of credit that they were eligible to claim from the Internal 
Revenue Service (IRS). These estimates were based on a random sample of 
1999 tax returns with the EIC claimed on the return. IRS audited these 
returns to determine the accuracy of the EIC claim and other tax return 
items, as part of their forthcoming tax-year 1999 EIC compliance study. 
The estimates of eligible claimants are based on the number of returns 
where the examiners did not reduce the EIC claim to zero. The estimates 
of the amounts of credit are based on the amounts corrected by the 
examiners for overclaims or underclaims on the returns. IRS conducted 
consistency and other tests on the data, and the audits were subject to 
quality review. 

Limitations of Our Analysis: 

The CPS does not contain all of the information needed to determine 
eligibility. Data such as capital gains and contributions to individual 
retirement accounts are not requested in the CPS survey. However, it is 
likely that the missing data have little effect on our participation 
estimates. These types of income and deductions are not common for the 
lower-income people who may be eligible for the credit. To verify this, 
we examined the tax returns of households in the 1996 Statistics of 
Income Public Use File, the most recent data available. We found that 
no more than 3 percent of households that met the other income limits 
for credit eligibility had these types of income and deductions. 

The CPS also does not have complete information for determining whether 
a child is resident long enough in a household to be a “qualifying 
child” for the purpose of determining the amount of credit that the 
households are eligible to claim. Children must reside in the household 
for more than half the year (a full year for foster children) in order 
to be qualifying children. The CPS survey asks only whether the child 
is resident in the household during the week in which the survey is 
conducted. This limitation in the CPS data means that some children 
reported in the survey may not meet the residency requirement while 
others who meet the requirement may not be reported. To test the likely 
impact of this limitation, we checked the low-income households that 
were surveyed in both the 1999 and 2000 March Supplements of the CPS. 
We found that 97 percent of the children who were living in these 
households in 2000 were also living in the same household in 1999. 

The CPS contains self-reported data from the survey respondents. Some 
analysts have raised concerns that this information may not be reported 
accurately. A National Research Council study that reviewed studies of 
the accuracy of the survey data concluded that wage and salary 
information appears to be fairly accurately reported in the CPS. The 
study also concluded that other types of income, such as interest and 
dividends, may be underreported but that this underreporting is probably
not critical for studies of low-income people for whom these are not 
important sources of income. The study did not review the accuracy of 
other household characteristics relevant to credit eligibility that are 
reported in the CPS. Another limitation of the CPS data is the possible 
underreporting of certain populations such as the homeless. 

As we noted in the letter, differences in the participation rates 
across household types may reflect actual taxpayer behavior. The lower 
participation rate for households with three or more children may 
indicate that taxpayers in those households may be more likely to be 
married and filing jointly which is a filing status with a higher 
income threshold for the requirement to file a tax return. Therefore,
fewer of these households may be required to file tax returns than 
households that have similar incomes but fewer children. A household 
that is required to file a tax return may be more likely to claim the 
EIC than a household that otherwise would not be required to file a 
return. The relatively low participation rate of households with no 
children may be due to the fact that these households receive 
significantly smaller benefits from the credit than do households with 
qualifying children. Or it may result from the fact that there is a 
relatively narrow income range in which taxpayers with no children are 
both above the filing threshold and below the income cut-off for EIC 
eligibility. [Footnote 5] Because we did not have CPS and IRS data for 
the same households, we could not examine characteristics of the 
eligible households that would enable us to test these and other 
factors that may affect participation. 

However, it is also possible that the variation in participation rates 
could result from limitations of the data we used. If, for example, low-
income households with no qualifying children inaccurately claimed one 
or two qualifying children and IRS did not detect all such cases of 
this misreporting, then the number of no-children households in IRS’ 
study would be undercounted, while the number of one- and two-children
households would be overcounted. An undercount of no-children 
households would mean that our participation rate for that group is 
understated. Conversely, an overcount of the other two groups would 
mean that our participation rates for them are overstated. 

The variation in participation rates across groups also could be 
inaccurate if IRS auditors involved in the EIC compliance study spent 
less effort (or had more difficulty) determining whether households had 
more than two qualifying children than determining whether taxpayers 
had one or two qualifying children. The number of children up to two 
has a significant effect on the amount of credit that all eligible 
households are allowed to claim. The presence of a third eligible child 
is important only if one of the first two children that a household 
identifies is determined to be ineligible. Moreover, taxpayers are not 
asked to identify more than two qualified children on schedule EIC when 
claiming the credit. If IRS counted some households that have three or 
more qualifying children as two-child households, then our estimate of 
the participation rate for households with three or more children would
be understated, and our estimated participation rate for two-child 
households would be overstated. The data collection instrument for IRS’ 
study did call for auditors to collect information on more than two 
qualified children. 

At the time that we were issuing this letter the Treasury Inspector 
General for Tax Administration (TIGTA) was about to issue a review of 
IRS’ 1997 and 1999 EIC compliance studies. We read a draft of the TIGTA 
review and discussed it with officials from TIGTA and IRS’ Office of 
Research, which had a leading role in the compliance studies. The TIGTA 
review does not directly address IRS’ counts of the number of eligible 
EIC participants. The review raises questions about potential 
inaccuracies in IRS’ estimates of allowable credits for 1999, which we 
report in table 2. However, the review does not provide a basis for us 
to determine the extent, if any, of actual inaccuracies. IRS strongly 
disagrees with TIGTA’s assessment and believes that their compliance 
estimates are reasonably accurate. We did not verify the accuracy of 
IRS’ study. 

[End of enclosure] 

Footnotes: 

[1] A qualifying child must meet a relationship test (with respect to 
the taxpayer claiming the credit), an age test, and a residence test. 
In tax year 2001 the maximum amount of credit that a taxpayer with no 
qualifying children can earn is $364. The maximum for a taxpayer with 1 
qualifying child is $2,428, and the maximum for a taxpayer with 2 or 
more qualifying children is $4,008. 

[2] See, for example, John Karl Scholz, “The Earned Income Tax Credit: 
Participation, Compliance, and Antipoverty Effectiveness,” National Tax 
Journal, Vol. 47, no. 1, (March 1994), pp. 63-87. 

[3] The sampling errors measure the extent to which samples of 
different sizes are likely to differ from the populations that they 
represent. Each of the sample estimates in tables 1 and 2 is surrounded 
by a 95-percent confidence interval indicating that we are 95-percent 
confident that the interval contains the actual population value. In 
the tables, the upper and lower limits of the intervals are indicated 
by the value added to and subtracted from the estimate. 

[4] In this letter, households are individuals or married couples. 
Eligibility is determined with respect to these persons according to 
the income, residency, family relationship and other rules of the EIC. 

[5] In fact, none of the taxpayers who file joint returns and are 
eligible for the no-child EIC have incomes above the filing threshold. 

[End of section] 

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