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Tax Enforcement: IRS Audit Processes Can Be Strengthened to Address a Growing Number of Large, Complex Partnerships

GAO-23-106020 Published: Jul 27, 2023. Publicly Released: Jul 27, 2023.
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Fast Facts

More businesses have been organizing as partnerships. This allows them to pass income and losses to their partners instead of being taxed as corporations. Between 2002 and 2019, the number of large partnerships—with over $100 million in assets and 100 or more partners—increased almost 600%.

The IRS audit rate for large partnerships has dropped to less than 0.5% since 2007. About 80% of audits conducted don't find tax noncompliance. This may suggest that IRS isn't choosing the riskiest returns to audit or doesn't know how to find noncompliance in these businesses.

Our recommendations would help IRS improve how it selects partnerships to audit.

Large partnerships are increasing in number and complexity, posing tax enforcement challenges.

Line graph showing the increase in large partnerships overtime (between 2002 and 2019)

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What GAO Found

In tax year 2019, there were 20,052 large partnerships, increasing nearly 600 percent since tax year 2002. Eighty-four percent of large partnerships reported providing finance and insurance services or real estate and rental leasing. Large partnerships can be complex with income or business expenses passing through multiple levels such that a partnership could be a partner in another partnership.

The Internal Revenue Service (IRS) audits few large partnerships—54 in tax year 2019—and the audit rate has declined since 2007. More than 80 percent of the audits resulted in no change to the return on average from tax years 2010 to 2018, double the rate of large corporate audits. For those that did change, the average adjustment was negative $264,000. IRS officials attributed the declining audit rate to resource constraints. The Inflation Reduction Act of 2022 (IRA) provided IRS with $45.6 billion for enforcement activities through the end of fiscal year 2031, and in response IRS identified large partnerships as an enforcement priority. About $1.4 billion of this funding was rescinded in 2023 with a White House briefing reporting an agreement to reduce future funding by $20 billion.

Audit Rate for Large Partnerships, 2007–2019

Audit Rate for Large Partnerships, 2007–2019

As part of its audit selection process, IRS uses statistical models to help review partnership returns for potential noncompliance, but the models were developed without using representative samples of returns and with untested assumptions. Additionally, IRS has not developed a plan to incorporate feedback from audit results into the models. Addressing these modeling issues could improve IRS's ability to better identify and audit noncompliant partnerships.

IRS planning documents state that it will expand enforcement efforts related to large, complex partnerships using IRA funding. However, IRS has not defined complexity or size in terms specific enough to guide enforcement efforts. IRS also has not developed measures to ensure that additional audits focus on these entities. Developing such a definition and specific outcome measures would help IRS develop plans, track resources used, and assess the results of these new investments in large partnership audits.

Why GAO Did This Study

Business activity has increasingly shifted toward legal structures known as partnerships and away from C corporations subject to the corporate income tax. A partnership is generally an unincorporated organization with two or more members that conducts a business and divides profits. Partnerships usually do not pay income taxes as entities but pass the net income or losses to partners, such as individuals or corporations, who then report the income and pay any applicable taxes.

GAO was asked to examine trends in large partnerships and IRS auditing of them. This report (1) summarizes the number and characteristics of large partnerships; (2) describes the resources used and results of audits of large partnerships; and (3) assesses IRS's efforts to identify potential noncompliance risks in large partnerships. For purposes of this report, large partnerships are defined as having $100 million or more in assets and 100 or more total partners.

GAO analyzed IRS data pertaining to business and audit activity for tax years 2002 through 2019, the most recent year for which complete data were available; compared IRS statistical models to relevant statistical modeling standards; interviewed agency officials; and held discussion groups with IRS staff.


GAO is making four recommendations to IRS, including improving the design of its models as well as developing guidance to define and measures to track large and complex partnership audits. IRS agreed with GAO's recommendations.

Recommendations for Executive Action

Agency Affected Recommendation Status
Internal Revenue Service The Commissioner of Internal Revenue should use representative sampling of partnership returns, including those on which IRS's current partnership models do not identify risk factors, to help identify additional noncompliance that may not be detected and to improve the agency's understanding of the models' effectiveness. (Recommendation 1)
IRS agreed with the recommendation. In January 2024, officials described a plan to test statistical models used to identify potential noncompliance risks among the largest partnerships by September 30, 2024. As part of this plan, officials said subject matter experts will review a sample of large partnership returns selected from all categories of identified risk. This is intended to improve the statistical models' ability to identify potential noncompliance. We will continue to monitor IRS's efforts to address our recommendation.
Internal Revenue Service The Commissioner of Internal Revenue should test and validate the key assumptions used in IRS's partnership models through analysis of data on audit outcomes or other research and develop a formal process for using audit results and other data as they become available to improve model performance. (Recommendation 2)
IRS agreed with the recommendation. In January 2024, IRS officials described plans to gather and utilize feedback throughout the examination process to improve modeling efforts. We will continue to monitor IRS's efforts to address our recommendation.
Internal Revenue Service The Commissioner of Internal Revenue should develop guidance defining large, complex partnerships and the characteristics of those entities. (Recommendation 3)
IRS agreed with the recommendation. In January 2024, officials reported they are working with IRS research officials to understand the partnership population and identify more specific segments of partnerships. We will continue to monitor IRS's efforts to address our recommendation.
Internal Revenue Service The Commissioner of Internal Revenue should identify and implement measures for tracking progress toward agency objectives that reflect the definitions and guidance for large, complex partnerships, which should include creating additional activity codes for IRS to track audit resources used and results. (Recommendation 4)
IRS officials reported in January 2024 that they partially agree with this recommendation. Officials agree that it is important to track progress. However, they do not agree that creating additional activity codes are necessary. They believe that the agency's existing codes are sufficient to track staffing and audit results of partnership compliance efforts. However, our review of audit data calls into question how effective using these codes has been. We found that IRS in recent decades audited few large partnerships. Further, the recent directive by the Secretary of the Treasury and IRS Commissioner to use Inflation Reduction Act funding to focus audit efforts on the largest and most complex partnerships makes it important that officials be able to identify such partnerships. We will continue to monitor IRS's efforts to address our recommendation.

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