You sign a purchase agreement to buy out a retiring limited partner. The fund manager hands you a stack of certifications, an affidavit, and a one-page memo from outside counsel warning you to "consider Section 1446(f)." The closing is in two weeks. The amount realized is $4 million.
If you read that warning and move on without acting, you may have just personally agreed to pay $400,000 in withholding tax to the IRS — on top of the purchase price — within twenty days of closing.
That is the trap of Section 1446(f). Buyers walk into partnership interest deals thinking withholding is a problem for U.S. real estate sales or for cross-border royalty payments. They learn the hard way that since 2018, almost every transfer of an interest in a U.S. trade-or-business partnership carries a 10% withholding obligation on the transferee unless an exception is properly documented. The seller does not write the check. You do.
This guide unpacks what the rule actually says, who it covers, the six exceptions that get you out from under it, the certifications you need on file before closing, and the bookkeeping discipline that keeps the whole thing defensible if the IRS ever asks for proof.
What Section 1446(f) Actually Requires
Section 1446(f) was added to the Internal Revenue Code by the 2017 Tax Cuts and Jobs Act. It was Congress's enforcement response to the Supreme Court loss in Grecian Magnesite Mining v. Commissioner, where the Tax Court held that gain on a foreign person's sale of a partnership interest was not U.S.-source effectively connected income (ECI). Congress did not like that outcome. It enacted two paired provisions:
- Section 864(c)(8) says a foreign partner's gain on the sale of a partnership interest is ECI to the extent the partnership itself would have generated ECI if it had sold all its assets at fair market value on the transfer date. That is the deemed sale rule.
- Section 1446(f) is the enforcement hammer. It requires the buyer to withhold 10% of the amount realized whenever any portion of the gain would be ECI under Section 864(c)(8).
The mechanics are blunt. If the seller is a foreign person and the partnership conducts a U.S. trade or business, the buyer must:
- Withhold 10% of the gross amount realized — not 10% of the gain, but 10% of the full purchase price plus any liability relief.
- Pay that amount to the IRS by the 20th day after the transfer date using Form 8288, U.S. Withholding Tax Return for Certain Dispositions by Foreign Persons.
- Issue Form 8288-A to the transferor as proof of withholding so the seller can credit it on their own U.S. tax return.
If the buyer fails to withhold, the partnership becomes secondarily liable. The partnership must then withhold from future distributions to the new partner until the deficiency is cured, plus interest and penalties. That is not a position any general partner wants to be in.
Why This Catches So Many Deals Off Guard
Three features of Section 1446(f) make it unusually punitive for buyers who are not paying attention.
The default is to withhold. Unlike FIRPTA where you presume a U.S. seller is selling U.S. real property and look for relief, Section 1446(f) flips that. If you cannot prove an exception applies, you withhold. The transferee bears the burden of documentation.
"Foreign person" is broader than people expect. It includes nonresident alien individuals, foreign corporations, foreign partnerships, foreign trusts, and foreign estates. A U.S. LLC owned 100% by a single nonresident alien is itself treated as a foreign person for these purposes because it is disregarded. A Cayman feeder fund, a BVI holding company, and a Singapore family office investor all trigger the rule.
Almost every operating partnership has some ECI exposure. If the partnership owns U.S. real estate, runs a U.S. business, or has employees on the ground, its deemed sale would generate at least some ECI. That is enough to pull the transfer into Section 1446(f) unless a more specific exception applies.
The combination means buyers need to assume Section 1446(f) applies and work backward from there, not assume it does not apply and react if challenged.
The Six Exceptions That Get You Out From Under
The final regulations under Treas. Reg. § 1.1446(f)-2(b) lay out six exceptions to the 10% withholding requirement for non-publicly-traded partnership interests. Each requires a specific certification, signed under penalties of perjury, in the buyer's hands before closing.
Exception 1: Non-Foreign Affidavit (the W-9 path)
If the transferor certifies that they are not a foreign person and provides a U.S. taxpayer identification number, no withholding is required. A correctly completed Form W-9 satisfies this in most cases. This is the cleanest exception and the one buyers should always check first.
Exception 2: No Realized Gain
If the transferor certifies that the transfer produces no realized gain — sale price equals or falls below adjusted basis — there is no underlying tax to enforce, so no withholding. The transferor needs basis records strong enough to back this up.
Exception 3: Less-Than-10% ECI Gain
If the partnership certifies that a hypothetical sale of all its assets would produce ECI gain that is less than 10% of the total gain (or no gain at all), the transfer falls outside the rule. The partnership signs this one, not the transferor, so the buyer needs to ask the partnership for the certificate well before closing.
Exception 4: Three-Year Lookback for Modest ECI Allocations
If the transferor was a partner in the partnership for each of the last three taxable years and the transferor's allocable share of ECTI in each of those years was both less than $1 million and less than 10% of the transferor's total distributive share of net income, the transferor can certify out. This is the long-tenured passive investor exception.
Exception 5: Treaty Benefit
If the transferor is eligible for an income tax treaty that exempts the gain from U.S. tax, withholding is excused on a properly executed treaty certification. This typically requires a Form W-8BEN or W-8BEN-E plus a treaty position statement. The treaty must actually cover gains on partnership interests, which not every U.S. treaty does cleanly.
Exception 6: Nonrecognition Transfer
If the transfer qualifies for nonrecognition under provisions like Section 721 contributions or Section 351 incorporations, withholding is excused. The transferee gets a written certification describing the nonrecognition provision and how it applies.
In every exception, the certification must be received by the transferee on or before the date of the transfer. After-the-fact paperwork does not work.
Publicly Traded Partnerships Are Their Own Universe
The rules above govern non-PTP interests — private equity funds, hedge funds, real estate JVs, operating LPs, professional service firms organized as LLCs, and so on. Interests in publicly traded partnerships such as energy MLPs trade through brokers, and the final regulations push the withholding obligation onto the broker rather than the buyer.
If you are buying units in an MLP through your brokerage account, you are not personally on the hook for Section 1446(f) compliance. Your broker either applies the 10% withholding to your sale proceeds or relies on broker-specific exceptions like the "qualified notice" published by the PTP. PTP qualified notices typically disclose whether 1446(f) withholding will apply at the unit level for any given quarter.
This split matters for fund administrators who run feeder structures with both PTP and non-PTP holdings. Different paperwork flows for different positions, and conflating the two is a common audit finding.
How the 10% Bite Compounds in Real Deals
Consider a foreign individual who sells a $5 million interest in a U.S. operating LLC that has $1 million in nonrecourse debt allocated to the seller. The seller's amount realized is $6 million — purchase price plus liability relief under Section 752. The required withholding is 10% of $6 million, or $600,000.
The seller's actual U.S. tax on the deemed-sale ECI portion might end up being $180,000. The seller will get the difference back when they file Form 1040-NR or 1120-F, but only after the return is processed. That refund cycle can run 12 to 24 months. Meanwhile the $600,000 sits with the Treasury, not with the seller.
Buyers should expect sellers to push hard for an applicable exception specifically because the cash-flow consequences are punishing. Modeling the timing impact in the purchase agreement — gross-ups, escrows, true-ups — is a routine negotiation point.
The Bookkeeping Discipline That Saves the Deal
Most Section 1446(f) failures are not aggressive tax positions. They are documentation failures. The closing happens, money moves, paperwork is incomplete, and three years later an IRS examiner asks for the certifications.
A defensible file for any partnership interest transfer involving a possibly foreign seller should contain:
- A copy of the executed purchase or assignment agreement showing the transfer date and amount realized
- The specific certification relied on (W-9, W-8BEN, treaty certificate, partnership ECI certificate, etc.), dated on or before the transfer
- A short memo from the buyer or its counsel explaining which exception applies and why
- The partnership's books showing the basis adjustment under Section 743(b) if a 754 election is in place
- If withholding was required, copies of Form 8288, Form 8288-A, the wire confirmation to the IRS, and the receipt provided to the transferor
Tracking these documents separately from the partnership's general ledger — but cross-referenced to the transfer transaction in the books — is what lets a tax adviser respond to an IRS letter without scrambling. Plain-text records with timestamps, signed PDFs, and a clear audit trail beat scattered email threads every time.
This is also where treating partnership interest transfers as a discrete bookkeeping event matters. The new partner's capital account, the basis adjustment, the residual gain allocation, and the withholding payment all need to tie. If your accounting system cannot show that they tie, an examiner will assume they do not.
Common Failure Modes to Avoid
A few patterns generate the most pain in practice.
Treating a U.S. LLC as automatically U.S. A single-member LLC owned by a foreign person is disregarded, which means the foreign owner is the transferor. The W-9 from the LLC will not save the buyer. Look through to the owner.
Relying on a stale certificate. A treaty certification from three years ago is not good enough. The buyer needs the certification dated at or before the transfer and matched to that specific transaction.
Ignoring liability relief in the amount realized. The 10% is calculated on the full amount realized, which under Section 752 includes the seller's share of partnership liabilities released on the transfer. Many buyers compute it on cash consideration alone and under-withhold.
Assuming the partnership will handle it. Section 1446(f) puts the primary obligation on the transferee. The partnership becomes secondarily liable only if the transferee fails to withhold. Buyers cannot delegate the obligation to the partnership.
Forgetting the 20-day deadline. Form 8288 and the withholding payment are due 20 days after the transfer, not by quarter-end or year-end. Missing that deadline triggers failure-to-pay and failure-to-file penalties even if the withholding itself was correct.
When Buyers Should Walk Through a Pre-Closing Checklist
Two weeks before closing on any partnership interest purchase, the buyer's team should be able to answer five questions:
- Is the seller a foreign person, or could it be one through a disregarded entity?
- Does the partnership conduct a U.S. trade or business, or hold U.S. real property interests treated as ECI?
- Which Section 1446(f) exception will be relied on, and does the buyer have the signed certification in hand?
- If no exception applies, what is the calculated 10% withholding on the gross amount realized including liability relief?
- Who will file Form 8288 and Form 8288-A by the 20-day deadline, and where is the IRS payment wiring?
If any answer is "we'll deal with it after closing," push the closing.
Keep Your Partnership Records Audit-Ready
Section 1446(f) compliance is one of those tax rules where the cost of getting it right is small and the cost of getting it wrong is enormous. A defensible record of certifications, transfer documents, basis adjustments, and withholding filings turns a potential examination into a paper-trail exercise. Without that record, even a legitimate exception becomes hard to defend years later when memories have faded and people have moved on.
Beancount.io gives you plain-text accounting with full version history, so every basis adjustment, capital account roll-forward, and withholding entry sits in a transparent ledger you can hand to auditors, tax counsel, or the IRS without reformatting. No black boxes, no vendor lock-in, no scrambling to reconstruct what happened at closing. Get started for free and see why funds, partnerships, and professional advisers are switching to plain-text accounting for the records that matter most.