IRC 4940 Private Foundation Excise Tax: Net Investment Income and Form 990-PF

Net Investment Income: What Goes In and What Stays Out

IRC 4940(c) defines net investment income as gross investment income plus net capital gain on property held for investment, reduced by ordinary and necessary expenses paid or incurred for the production of that income. The calculation runs on its own track -- separate from the foundation's income tax computation (if any) -- under the mechanics of Treas. Reg. 53.4940-1.

Gross Investment Income

Gross investment income includes interest, dividends, rents, royalties, and payments with respect to securities loans under IRC 512(a)(5). Income from sources that would ordinarily generate unrelated business taxable income (UBTI) is also included when received by a private foundation, because private foundations are not subject to the general UBTI framework -- they pay the IRC 4940 excise tax instead.

Allowable Deductions

Expenses that are ordinary, necessary, and directly connected to the production of investment income reduce gross investment income. Common deductions include investment advisory fees, custodial charges, safe-deposit box rent allocable to investment securities, and a proportionate share of general administrative expenses allocable to investment activity. Depreciation on investment property is allowable under the straight-line method only (Reg. 53.4940-1(e)(1)). No deduction is allowed for federal income taxes, state and local income taxes, or the IRC 4940 excise tax itself.

Items Excluded from NII

Two categories of income are excluded from the NII base:

• Program-related investment income. Income generated by investments that qualify as program-related investments (PRIs) under IRC 4944(c) -- loans and equity positions made primarily to accomplish exempt purposes, not for investment return -- is excluded from NII. Proper PRI classification is essential; misclassification can expose a foundation to IRC 4944 jeopardizing investment taxes as well.
• Exempt function income. Revenue that is directly related to the foundation's charitable purposes -- admission fees, tuition income for an operating school, etc. -- is excluded from gross investment income and therefore from NII.

Capital Gains Treatment Under IRC 4940

Net capital gains on property held for investment are included in NII. "Net" means that capital losses on investment property may offset capital gains in the same tax year, but excess capital losses do not carry over to reduce NII in a future year -- unlike the carryover rules that apply under general income tax principles. A foundation that sustains losses in excess of gains in one year receives no NII benefit from those losses in subsequent years.

Pre-1970 Basis Election

A private foundation that held appreciated property on December 31, 1969 may elect, under Reg. 53.4940-1(f)(2), to substitute the fair market value of that property as of December 31, 1969 for its actual cost basis when computing gain or loss on a subsequent sale. Because many foundations received large gifts of appreciated stock or real estate before 1970, the FMV election can substantially reduce the capital gain component of NII.

Loss Netting and Carryover Rules

Within a single tax year, capital losses on investment property offset capital gains for NII purposes. If losses exceed gains, NII for the year is reduced to zero from the capital gain component -- but the excess loss disappears rather than carrying forward. There is no capital loss carryback or carryforward for purposes of IRC 4940. Practitioners should model the timing of asset dispositions accordingly, particularly for foundations with large unrealized gains and losses in the same portfolio.

Section 4940(d) Operating Foundation Exemption

IRC 4940(d) provides a complete exemption from the excise tax for private operating foundations that satisfy the qualifying distribution test. The exemption is not self-executing and must be earned anew each tax year.

Definition of a Private Operating Foundation

A private operating foundation, defined under IRC 4942(j)(3), is a private foundation that expends substantially all of its income (at least 85% of its adjusted NII, or its minimum investment return, whichever is less) directly for the active conduct of charitable activities. Operating foundations run programs directly -- a museum, a research institute, a library -- rather than making grants to other organizations.

The Qualifying Distribution Test for 4940(d)

To qualify for the 4940(d) exemption, a private operating foundation must make qualifying distributions during the tax year equal to or exceeding 85% of its adjusted net investment income. Qualifying distributions include amounts paid to accomplish one or more exempt purposes directly, reasonable and necessary administrative expenses, and amounts paid to acquire assets used directly in exempt activities.

Maintaining Operating Foundation Status

Operating foundation status requires continuous compliance with the income test (85% distribution requirement), the assets test (65% of assets used in exempt activities), and the endowment or support test, as described in IRC 4942(j)(3). A foundation that fails any prong loses its operating foundation status and becomes subject to both the IRC 4940 excise tax and the IRC 4942 distributable amount requirement. Counsel should schedule an annual 4942(j)(3) compliance review alongside the Form 990-PF preparation cycle.

Estimated Tax Obligations and Form 990-W

Private foundations subject to the IRC 4940 excise tax are required to make quarterly estimated tax installments under the rules of IRC 6655, as applied to tax-exempt organizations. The statutory framework mirrors the corporate estimated tax rules rather than the individual rules.

Quarterly Installment Due Dates

For calendar-year foundations, quarterly installments are due on the 15th day of the 5th, 6th, 9th, and 12th months of the tax year -- typically May 15, June 15, September 15, and December 15. Each installment must equal at least 25% of the required annual payment. The required annual payment is the lesser of (a) 100% of the tax shown on the current year's return or (b) 100% of the tax shown on the prior year's return.

Form 990-W Mechanics

Form 990-W (Estimated Tax on Unrelated Business Taxable Income for Tax-Exempt Organizations) serves as the worksheet for computing each quarterly installment. The foundation enters its estimated NII for the year, applies the 1.39% rate, and computes the installment. The form also provides the annualized income exception computation, which allows a foundation whose income is weighted toward later quarters to reduce earlier installments without penalty.

OBBBA Legislative Context: The Near-Miss Tiered Rate

The One Big Beautiful Budget Act (OBBBA), passed by the House in 2025, included a provision that would have reinstated a tiered excise tax rate structure under IRC 4940. Under the House-passed version, foundations whose qualifying distributions fell below a specified threshold -- measured as a percentage of assets -- would have faced a rate higher than 1.39%. Foundations distributing above the threshold would have retained the 1.39% rate or potentially received a lower rate.

The Senate stripped the IRC 4940 tiered-rate provision during conference, leaving current law -- the flat 1.39% rate -- unchanged. The provision did not become law.

Interaction Between IRC 4940 and IRC 4941 Self-Dealing

IRC 4941 imposes a two-tier excise tax on self-dealing transactions between a private foundation and a disqualified person. The first-tier tax is 10% of the amount involved, imposed on the disqualified person (not the foundation); the foundation's managers who knowingly participated face a separate 5% tax. A second-tier tax of 200% applies if the transaction is not corrected within the taxable period.

NII Deductibility of IRC 4941 Taxes

Excise taxes paid under IRC 4941 are not deductible in computing net investment income for purposes of IRC 4940. The regulations make clear that only expenses incurred for the production of investment income may reduce the NII base; penalty-type excise taxes imposed for violations of the private foundation rules do not qualify as production-of-income expenses. A foundation that pays substantial self-dealing taxes reduces its cash but does not reduce its 4940 tax base.

Form 4720 Filing Obligation

Both the IRC 4940 excise tax and any IRC 4941 self-dealing taxes are reported on Form 4720, Return of Certain Excise Taxes Under Chapters 41 and 42 of the Internal Revenue Code. The foundation files Form 4720 for its IRC 4940 liability; the disqualified person files a separate Form 4720 for the IRC 4941 first-tier tax. Foundation managers subject to the 5% manager-level tax also file separately. Counsel should coordinate the preparation of all Form 4720 filings to ensure consistent reporting of the amount involved across all filers. See also IRC 4958 intermediate sanctions for the analogous excess benefit transaction rules that apply to public charities.

NII Calculation Worksheet: Include/Exclude Reference

Key Compliance Traps for Private Foundation Advisors

The following issues represent the highest-frequency errors observed in IRC 4940 compliance engagements. Each reflects a place where the IRC 4940 rules depart from intuitions built on general income tax principles.

NII vs. Taxable Income Confusion

The most common IRC 4940 error is treating NII as a derivative of the foundation's income tax return. NII is calculated under an entirely separate statutory framework, using different expense allocation rules, different depreciation methods, and a capital gain/loss netting rule that has no carryover component. Foundations that engage income tax preparers without specific private foundation experience are particularly vulnerable here.

Operating Foundation Status: Annual Re-Qualification

Private operating foundation status is determined annually. A foundation that qualified in prior years does not carry that status forward automatically. The 85% qualifying distribution test must be met each year, and the Form 990-PF, Part XIV documentation must affirmatively show it was met. Foundations that expand their endowment without proportionally increasing program expenditures can drift into non-compliance without a structured annual review.

Estimated Tax Timing

Investment income is frequently concentrated in the first half of the calendar year for foundations holding dividend-paying equities and bond portfolios. If the foundation does not make estimated payments calibrated to that income timing, the IRC 6655 penalty applies to the early-quarter shortfalls even if the foundation writes a large check in December. Use the annualized income exception on Form 990-W to smooth installments when income is unevenly distributed across quarters.

Form 990-PF PRI Classification

Program-related investments must be identified and tracked separately from portfolio investments. Income from PRIs is excluded from NII; income from instruments that look like PRIs but do not satisfy the IRC 4944(c) tests is included. The Form 990-PF, Schedule I classification should be reviewed with counsel -- not just the accounting staff -- because it turns on a legal standard (primary purpose) rather than an accounting standard.

Frequently Asked Questions