A side letter in private equity is a separate, bilateral agreement between a fund’s general partner and a single limited partner that changes or adds to the terms of the fund’s main limited partnership agreement for that one investor. The partnership agreement still governs the fund as a whole, but the side letter creates a customized overlay on top of it, and where the two conflict, the side letter controls for the investor who signed it. Large institutional funds routinely execute dozens of these across their investor base.
How a Side Letter Fits Alongside the Partnership Agreement
The limited partnership agreement is the document that sets the rules for investments, management fees, carried interest, and the obligations of the manager and the investors. It is written to treat all limited partners uniformly. A side letter sits next to that document and carves out exceptions for a particular investor, usually negotiated one-on-one during the fundraising period before the fund’s final close.
That structure exists because institutional capital has genuinely different needs. A state pension fund bound by transparency laws and a sovereign wealth fund with religious investment restrictions cannot operate on identical terms, and neither wants its requirements broadcast to every other investor in the fund. Side letters let the manager accommodate both without rewriting the partnership agreement around either.
What a Side Letter Typically Covers
Regulatory and ERISA Protections
Pension funds and other benefit plan investors subject to the Employee Retirement Income Security Act face a specific issue: if too much benefit plan money flows into a fund, the fund’s underlying assets can be reclassified as “plan assets” under federal regulations, which pulls the general partner into ERISA’s fiduciary rules and prohibited transaction restrictions. The standard workaround is structuring the fund to qualify as a venture capital operating company or a real estate operating company, both of which are defined by federal regulations and require the fund to meet specific investment and management thresholds. A VCOC, for example, must hold at least 50 percent of its assets in operating companies where the fund exercises management rights. Side letters with pension investors often lock in a representation that the fund will maintain one of these exemptions throughout its life.
Tax Protections for Sovereign Investors
Foreign government investors use side letters to preserve their tax-exempt status under Section 892 of the Internal Revenue Code, which exempts certain U.S.-source investment income earned by foreign governments from federal tax. The exemption is lost when income comes from commercial activities or flows through a “controlled commercial entity” in which the government holds 50 percent or more of the interest by value or voting power. A sovereign investor’s side letter will typically require the general partner to notify it before the fund makes any investment that could jeopardize Section 892 status, and may grant excusal rights for those specific deals.
Enhanced Reporting
Public pension funds may need detailed portfolio company data to comply with state freedom-of-information laws. Endowments and foundations may require ESG metrics. Insurance company investors may need financial data formatted for regulatory filings. Side letters commit the general partner to produce this additional information, often within a specified number of business days after the standard reporting period. Because these provisions don’t change the fund’s economics for anyone else, they tend to be among the least contested.
Excusal Rights
Excusal rights let an investor opt out of specific investments that conflict with its internal policies, legal restrictions, or organizational charter. A religious endowment might need to avoid alcohol or gambling companies; a government pension fund might be prohibited from investing in countries under sanctions. When an investor is excused, its capital commitment for that deal is typically reallocated among the remaining limited partners or reduced, and the excused investor neither funds nor benefits from the excluded investment. General partners usually require advance notice and limit excusal rights to genuinely prohibited investments rather than letting an investor cherry-pick based on expected returns.
Co-Investment Rights
Co-investment provisions give an investor the chance to put additional capital into specific deals alongside the fund, usually on more favorable economic terms and often with reduced fees or no fees on the co-invested capital. The blended effect lowers the investor’s overall cost of accessing the manager’s deal flow. Managers tend to reserve co-investment rights for the largest commitments, returning investors from prior fund vintages, and strategically important partners. The strength of the language matters: a vague acknowledgment that the investor is “interested in co-investment opportunities” is very different from a contractual right of first look at every deal above a certain size.
Fee Adjustments
Discounts on management fees or carried interest do appear in side letters, though they cluster among certain investor types. Managers typically offer reduced fees to four groups: early-close investors who anchor the fundraise, returning investors from prior vintages, investors writing unusually large checks, and strategically important partners the manager wants to cultivate. A first-close investor committing a significant share of the fund’s target might negotiate a management fee reduction of 25 basis points or more; a smaller investor coming in at the final close has little leverage to ask for the same.
Most Favored Nation Clauses
Because side letters are negotiated individually, the biggest investors would otherwise capture every favorable term. A most favored nation clause is the counterweight. An investor holding this right can review the terms granted to other investors through their side letters and elect to add any of those terms to its own agreement. If the general partner gives one investor a fee discount and another investor holds an MFN right, the second investor can claim the same discount.
The review typically happens after the final close, once all side letters are executed. The general partner circulates a summary of granted terms to investors with MFN rights, and those investors have a specified window to make their elections.
Carve-outs are where the real negotiation happens. Terms granted based on commitment size are the most common exclusion, so a $50 million investor with an MFN right generally cannot claim a discount that a $500 million investor received for the scale of its commitment. Tax-specific provisions are also typically carved out, since a VCOC representation matters to a pension fund and is irrelevant to a family office. Experienced investors push to narrow these carve-outs; managers push to keep them broad.
Are Side Letter Terms Confidential?
Historically, yes. Partnership agreements and their related documents are not publicly disclosed and are usually subject to strict confidentiality provisions, so unless an investor holds an MFN right or the manager voluntarily shares information, a limited partner generally has no visibility into what terms other investors received. Public pension funds subject to open-records laws are a partial exception; they may have limited ability to keep their own side letter terms confidential regardless of what the agreement says.
Are Side Letters Legally Binding?
Side letters are binding contracts. They satisfy the standard formation requirements, with the investor’s capital commitment providing the consideration, and where a side letter grants rights that differ from the partnership agreement, those rights govern for the investor who signed it.
The main enforceability risk comes from integration clauses. Most partnership agreements state that the agreement represents the entire understanding between the parties, which could in theory invalidate outside arrangements. Fund counsel prevents that outcome by including a carve-out in the partnership agreement that explicitly authorizes the general partner to enter into side letters, and that carve-out preserves the side letter’s legal force.
If a general partner fails to honor a side letter commitment, the investor’s remedies are the same as for any breach of contract: damages, or in some cases a court order requiring the manager to perform the specific obligation. A breach is a dispute between the manager and that one investor, not a partnership-wide issue. Side letters typically remain in effect for as long as the investor holds its interest in the fund and terminate automatically when the investor withdraws or the fund winds down.
Where Regulation Currently Stands
In August 2023, the SEC adopted the Private Fund Adviser Rules, which included Rule 211(h)(2)-3. That rule would have prohibited fund managers from granting preferential terms the manager reasonably expected would materially harm other investors, and would have required written disclosure of all other preferential treatment to current and prospective investors. The SEC identified preferential redemption rights and information access as the arrangements most likely to damage non-favored investors during periods of market stress.
The rules never took effect. On June 5, 2024, the U.S. Court of Appeals for the Fifth Circuit vacated the entire rulemaking, holding that the SEC exceeded its statutory authority and that no part of the final rule could stand. Side letter practices remain governed primarily by contract law, fiduciary duty principles, and the general anti-fraud provisions of the securities laws rather than by any side-letter-specific regulatory framework. Managers are not required to disclose side letter terms to other investors unless the fund’s own documents, such as an MFN clause, or state law independently create that obligation. The SEC can still bring enforcement actions when undisclosed preferential treatment amounts to fraud or a breach of fiduciary duty, but the comprehensive disclosure regime it envisioned is not currently in force.