The rules and requirements for a private foundation come from Chapter 42 of the Internal Revenue Code and cover six main areas: an annual minimum payout, an excise tax on investment income, a prohibition on transactions with insiders, limits on business ownership, restrictions on risky investments and political activity, and mandatory annual reporting on Form 990-PF. Violations carry excise taxes that start modestly and can reach 200% of the amount involved.1Internal Revenue Code, Chapter 42
What Counts as a Private Foundation
A private foundation is a 501(c)(3) charitable organization funded and controlled by a single source — typically one donor, one family, or one corporation — rather than by broad public support. Every 501(c)(3) is presumed to be a private foundation unless it proves otherwise to the IRS. Public charities escape the classification by meeting the support tests in Section 509(a), which private foundations fail because their money comes from a concentrated source.
Within the category, the IRS distinguishes non-operating foundations from operating foundations based on how they spend. Non-operating foundations are grant-makers: they invest an endowment and distribute funds to other charities. Operating foundations run their own charitable programs directly — a museum, a research institute, a service provider — and must spend at least 85% of adjusted net income (or minimum investment return, whichever is less) on those activities. The distinction matters because several rules below, including the payout requirement and donor deduction limits, apply differently to each type.
The 5% Annual Payout Requirement
Section 4942 requires every non-operating private foundation to distribute a minimum amount for charitable purposes each year. The baseline is 5% of the average fair market value of the foundation’s non-charitable-use assets, essentially the investment portfolio, reduced by certain taxes the foundation already paid.
Qualifying distributions include direct grants to charities, reasonable administrative expenses tied to charitable activities, and purchases of assets the foundation uses directly for its exempt purposes. Grants to organizations controlled by the foundation or its disqualified persons generally do not count.
Miss the threshold and the foundation owes a 30% excise tax on the shortfall. If the underdistribution isn’t corrected by the end of the correction period, the tax jumps to 100% of the remaining amount. The IRS tracks distributions through Form 990-PF, so the math is easy to audit.
The 1.39% Tax on Investment Income
Under Section 4940, private foundations pay a flat 1.39% excise tax on net investment income each year. The tax applies to interest, dividends, rents, royalties, and net capital gains from asset sales. Congress set the flat rate in 2020, replacing a two-tier system that toggled between 1% and 2% depending on distribution levels.
For a foundation with a $100 million endowment generating $4 million in investment income, the annual bill comes to roughly $55,600. The tax is reported and paid through Form 990-PF and funds IRS oversight of the sector.
Self-Dealing: No Transactions With Insiders
Section 4941 prohibits virtually any financial transaction between a private foundation and a “disqualified person,” regardless of whether the deal is fair or even favorable to the foundation. This is where most compliance problems arise, usually because board members underestimate how far the rules reach.
Who Is a Disqualified Person
The category covers substantial contributors to the foundation, foundation managers (officers, directors, trustees), and anyone who owns more than 20% of an entity that is itself a substantial contributor. Family members are included, but the definition is narrower than most people assume: it covers a spouse, ancestors, lineal descendants, and spouses of lineal descendants. Siblings are specifically excluded. Corporations, partnerships, and trusts are disqualified if more than 35% of their ownership is held by other disqualified persons.
What Counts as Self-Dealing
Prohibited transactions include selling or exchanging property between the foundation and a disqualified person, leasing property in either direction, lending money, paying unreasonable compensation, and transferring foundation income or assets for a disqualified person’s benefit. Even a sale confirmed by an independent appraiser as at or above market value is still prohibited. Fairness is not a defense.
Penalties
The initial excise tax falls on the disqualified person: 10% of the amount involved for each year (or partial year) the transaction goes uncorrected. A foundation manager who knowingly participated owes a separate 5% per year, capped at $20,000 per act. If the transaction isn’t corrected within the taxable period, the tax on the disqualified person jumps to 200% of the amount involved, and a manager who refuses to help correct it owes 50%.
Limits on Business Ownership
Section 4943 caps how much of a business a private foundation and its disqualified persons can own together. Combined permitted holdings in an incorporated business are 20% of voting stock, with the foundation’s share reduced by whatever the disqualified persons hold. Excess holdings trigger an initial 10% excise tax on the value of the excess, escalating to 200% if not divested within the correction period.
The rule prevents private foundations from serving as holding companies for family businesses. A foundation that inherits a controlling stake through a bequest typically has five years to bring holdings below the limit, with longer transitions available in some situations.
Investments That Put the Mission at Risk
Section 4944 penalizes investments that threaten the foundation’s ability to carry out its charitable purpose. The statute doesn’t ban specific asset classes. Instead, the IRS looks at whether the investment, when made, reflected a lack of reasonable business care and prudence. Highly speculative positions without a diversification strategy are the classic example.
The initial tax is 10% of the amount invested for each year the investment remains in jeopardy. Managers who knowingly approved it face a 10% tax as well. If the investment isn’t removed from jeopardy within the correction period, the foundation owes an additional 25%, and managers who refuse to act owe 5%.
Program-related investments (PRIs) are carved out of these rules. A PRI is an investment whose primary purpose is advancing the foundation’s charitable mission, such as a below-market loan to a nonprofit affordable housing developer. To qualify, income production or asset appreciation cannot be a significant purpose, and the investment cannot be used for lobbying or political campaigns.
Lobbying and Political Activity Restrictions
Private foundations face tighter limits than public charities. Under Section 4945(d), any amount spent trying to influence legislation, whether through direct lobbying or grassroots campaigns urging the public to contact lawmakers, is a “taxable expenditure” subject to a 20% excise tax on the foundation. Managers who knowingly approve the spending owe a separate 5%. Uncorrected, those penalties climb to 100% on the foundation and 50% on managers.
Political campaign activity is more restricted still. A private foundation cannot spend any money to support or oppose a candidate for public office. Doing so jeopardizes tax-exempt status entirely.
Three exceptions exist. A foundation can publish nonpartisan research and analysis that touches on legislative topics, as long as it presents facts thoroughly enough for readers to draw their own conclusions. It can provide technical assistance to a government body that requests it in writing. And it can advocate on matters directly affecting its own existence, tax-exempt status, or the deductibility of contributions to it.
Annual Filing and Public Disclosure
Every private foundation must file Form 990-PF each year, due by the 15th day of the fifth month after the fiscal year ends. For calendar-year foundations, that’s May 15. An automatic six-month extension is available with Form 8868, pushing the deadline to November 15.
The form requires detailed reporting of total assets, investment income, the excise tax calculation, all grants and charitable distributions, and the names and compensation of every officer, director, trustee, and foundation manager. The IRS uses it to verify compliance with the payout requirement, self-dealing rules, and business holdings limits.
Form 990-PF is a public document. Foundations must make it available for public inspection for three years from the filing due date or the actual filing date, whichever is later. Most returns appear on sites like GuideStar or the foundation’s own website soon after filing, so journalists, grant seekers, and regulators can see exactly how much a foundation holds, distributes, and pays its managers.
Missing the filing deadline for three consecutive years triggers automatic revocation of tax-exempt status under Section 6033(j). Reinstatement requires a new application and potentially back taxes. Smaller family foundations without dedicated staff have been caught by this.
Donor Deduction Limits
Donors to private foundations face tighter deduction caps than donors to public charities. For 2026, with the temporary TCJA increase expired, cash contributions to a public charity are deductible up to 50% of the donor’s adjusted gross income. Cash to a non-operating private foundation is capped at 30% of AGI. Appreciated property like real estate or closely held stock is limited to 20% of AGI for private foundation gifts, versus 30% for public charities.
There’s another catch. When you give appreciated property to a non-operating private foundation, you generally deduct only your cost basis, not fair market value. The main exception is publicly traded stock held longer than one year, which qualifies for a fair-market-value deduction. Contributions exceeding AGI limits carry forward for up to five years. Operating foundations get more favorable deduction limits that resemble those for public charity contributions.
Ending or Converting a Foundation
Closing a private foundation isn’t as simple as filing a final return. Section 507 governs termination and is designed to keep charitable assets from ending up back in private hands.
The cleanest exit is distributing all net assets to one or more public charities that have been in continuous operation for at least 60 months. Done properly, this avoids the termination tax entirely. Alternatively, a foundation can convert to public charity status by meeting the public support tests for 60 consecutive months after notifying the IRS of its intent.
Involuntary termination is far worse. If the IRS finds willful and repeated violations of the Chapter 42 rules, or a single willful and flagrant act, it can impose a termination tax equal to the lesser of the foundation’s aggregate tax benefit from its entire history of exempt status or the value of its net assets. That can wipe out the foundation. The IRS has discretion to abate the tax if the foundation corrects course and distributes assets to qualifying public charities.