Who must file Form 8865, and which category applies?

Form 8865 is an information return — it reports a US person's interest in, and the activity of, a foreign partnership. It does not, by itself, compute a tax. But the obligation is easy to miss and expensive to get wrong: a late, incomplete, or inaccurate Form 8865 can draw a $10,000 penalty per partnership per year under §6038(b) (with continuation penalties), a §6038B penalty of 10% of the value of contributed property for an unreported contribution, or a $10,000 §6679 penalty for an unreported acquisition or disposition — and under §6501(c)(8) the assessment statute of limitations for the return generally does not begin to run until the form is filed.

This guide is about the threshold question that precedes the schedules: does an obligation exist for this person, for this foreign partnership, for this year — and in which of the four filer categories? It works that determination the way a preparer should: confirm the entity is a partnership at all, pin down the statutory building blocks, run the §267(c) attribution that drives the thresholds, then assign every category that applies.

In plain terms there is no single "you must file Form 8865" rule, and merely being a partner is not itself a trigger. There are four categories, each with a different trigger: controlling the partnership, holding at least a 10% interest while US persons together control it, contributing property to it, or having a reportable event during the year. The same US person can fall into more than one. The work is figuring out which categories — if any — a given US person falls into for a given foreign partnership.

The building blocks

Every category is defined in terms of a few statutory concepts. Pin these down and the categories fall out.

Is it even a foreign partnership? (classify first)

Form 8865 is for foreign partnerships. Before running any test below, classify the entity, because a different classification points to a different form entirely:

• A per se corporation — a foreign entity on the §301.7701-2(b)(8) list (e.g., a UK plc, a German AG, a French SA) — is always a corporation; no election is available.
• Any other foreign entity is an eligible entity with a default classification under §301.7701-3(b)(2): with two or more members, it is a partnership if at least one member lacks limited liability, or an association taxable as a corporation if all members have limited liability; a single-member entity that lacks limited liability is a disregarded entity.
• An eligible entity can elect out of that default with a check-the-box election on Form 8832.

A foreign partnership points to Form 8865; a foreign corporation points to Form 5471; a foreign disregarded entity to Form 8858; and a 25%-foreign-owned US entity to Form 5472. Get this wrong and the rest of the analysis is on the wrong form. A "foreign partnership" for this purpose is a partnership described in §7701(a)(5) (Treas. Reg. §1.6038-3(b)(7)).

"US person" — who can be a filer

A Form 8865 filer is a US person as defined in §7701(a)(30): a US citizen or resident individual, a domestic partnership, a domestic corporation, an S corporation, and a non-foreign estate or trust. The filing obligation is tested at that person's level — so a domestic partnership or S corporation that holds the foreign-partnership interest is itself the US-person filer (you do not look through it to its own partners to decide whether it must file).

"Control" — the §6038(e)(3) more-than-50% interest

The control concept that defines a Category 1 filer is §6038(e)(3) — the foreign-partnership control test. This is a recurring trap: it is not §6038(e)(2), which is the more-than-50%-of-vote-or-value test for a foreign corporation (the test that drives Form 5471 Category 4). A partnership has no "voting power"; its control test is measured in interests:

A person is in control of a partnership if such person owns directly or indirectly more than a 50 percent interest in such partnership.

— IRC §6038(e)(3)(A)

And a "50-percent interest" is defined in the alternative — capital, profits, or deductions/losses:

a 50-percent interest in a partnership is— (i) an interest equal to 50 percent of the capital interest, or 50 percent of the profits interest, in such partnership, or (ii) to the extent provided in regulations, an interest to which 50 percent of the deductions or losses of such partnership are allocated.

— IRC §6038(e)(3)(B)

Because the test is disjunctive, a US person who holds only a sliver of capital can still control the partnership if more than 50% of its profits — or more than 50% of its deductions or losses — are allocated to that person. You have to check all three measures, not just the capital account.

The "10-percent interest"

The same definition, with "10 percent" substituted, gives the 10-percent interest that matters for Category 2 and for the §6046A reportable-event tests:

A 10-percent interest in a partnership is an interest which would be described in subparagraph (B) if "10 percent" were substituted for "50 percent" each place it appears.

— IRC §6038(e)(3)(C)

So a 10-percent interest, too, is met by 10% of capital, 10% of profits, or an allocation of 10% of deductions or losses.

In plain terms "control" here is not about votes — a partnership has none. It is about owning more than half of the capital, the profits, or the loss allocations. Any one of the three is enough. The 10% line works the same way, one rung down. So before you can place anyone in a category, you need the partnership agreement's capital, profits, and loss-sharing percentages — not just the headline ownership split.

The engine: §267(c) constructive ownership

Every threshold above — more-than-50%, 10% — is tested after applying constructive ownership. For a foreign partnership the relevant rules are §267(c) (other than §267(c)(3)), brought in by §6038(e)(3)(B)'s flush language and Treas. Reg. §1.6038-3(b)(4). This is a different attribution regime from the §958(b)/§318 rules that drive CFC status on Form 5471, and conflating them is a common error.

The operative §267(c) rules are:

• §267(c)(1) — entity to owner. An interest owned by or for a corporation, partnership, estate, or trust is owned proportionately by its shareholders, partners, or beneficiaries.
• §267(c)(2)/(4) — family. An individual is treated as owning an interest owned by the individual's family, and the family is defined broadly:

The family of an individual shall include only his brothers and sisters (whether by the whole or half blood), spouse, ancestors, and lineal descendants.

— IRC §267(c)(4)

• §267(c)(5) — re-attribution. An interest owned constructively under (c)(1) is treated as actually owned for re-applying the rules, but an interest attributed within a family under (c)(2) is not re-attributed to make a second person the owner.
• §267(c)(3) does NOT apply. The partner-to-partner attribution rule is switched off for §6038 partnership purposes — so two unrelated partners are not treated as owning each other's interests.

Two features set §267(c) apart from the CFC rules, and both can pull a US person into a filing obligation that the §318 rules would not:

Example — siblings count. USP A owns 0% of foreign partnership FP B directly. A's brother, a US citizen, owns a 12% interest in FP B. Under §267(c)(4), A is treated as owning that 12% for the §6038(e)(3) interest tests — even though A holds nothing directly, and even though §318 (which omits siblings) would not attribute it. That constructive 12% can make A a Category 2 filer, or count A into the group that controls FP B. The same sibling interest would be invisible to the Form 5471 CFC analysis.

In plain terms the threshold tests are rarely "what does my client own on paper." Family counts — and for a partnership, family reaches siblings, not just spouse-and-children. A client who owns nothing directly can be a filer because a brother, sister, parent, or child owns a slice. Run the attribution across the whole family and ownership chain before you decide a category.

The four filer categories

A single US person can fall into more than one category for the same partnership in the same year, and the schedule requirements of each apply. Assign every category that fits.

Category 1 — control of the partnership

A US person who controlled the foreign partnership — owned more than a 50% interest, under §6038(e)(3) and after §267(c) attribution — at any time during the partnership's tax year is a Category 1 filer (Treas. Reg. §1.6038-3(a)(1)). There can be more than one Category 1 filer for the same partnership (a single filing may then cover them all — see Exceptions and relief).

Example. USP A owns a 60% capital and profits interest in FP B. A owns more than a 50% interest, so A controlled FP B and is a Category 1 filer for the year — and files the full Category 1 schedule set.

Category 2 — a 10% interest while the partnership is US-controlled

A US person who, at any time during the partnership's year, owned a 10% or greater interest while the partnership was controlled by US persons each owning at least a 10% interest is a Category 2 filer. The statutory hook is §6038(a)(5):

In the case of a foreign partnership which is controlled by United States persons holding at least 10-percent interests (but not by any one United States person), the Secretary may require each United States person who holds a 10-percent interest in such partnership to furnish information relating to such partnership, including information relating to such partner's ownership interests in the partnership and allocations to such partner of partnership items.

— IRC §6038(a)(5)

Two points decide most Category 2 questions. First, "US-controlled" means US persons each owning ≥10% who collectively own more than 50% — and the collective test uses each person's distinct, non-overlapping interest. Do not sum overlapping attributed interests; constructive attribution can make percentages double-count, and adding them can exceed 100%. Second — and this is the rule that most often flips the answer:

If the partnership has a Category 1 filer at any time during the year, no one is a Category 2 filer. Category 2 exists for the case where US persons together control a partnership that no single US person controls (§6038(a)(5)'s "but not by any one United States person"); the moment one US person crosses 50%, that person is Category 1 and Category 2 switches off for everyone (Treas. Reg. §1.6038-3(a)(2)).

Example. USP A owns 15% of FP B and USP C owns 40%; both are US persons, each owns at least 10%, and together they own 55% — more than half. No single US person controls FP B, so both A and C are Category 2 filers. Now change one fact: if C instead owned 60%, C controls FP B and is a Category 1 filer — and because FP B now has a Category 1 filer, no one is a Category 2 filer, including A. A's 15% has not changed, but A's filing obligation has disappeared, because the category that caught A is suppressed.

Category 3 — contributing property to the partnership (§6038B)

A US person who contributes property to a foreign partnership in a §721 transfer must report under §6038B. The statute reaches the contribution directly:

Each United States person who … transfers property to … a foreign partnership in a contribution described in section 721 or in any other contribution described in regulations prescribed by the Secretary [shall furnish the prescribed information].

— IRC §6038B(a)(1)(B)

Reporting is required if either test is met (Treas. Reg. §1.6038B-2(a)(1)):

1. The 10% test — immediately after the contribution, the US person owns directly, indirectly, or by attribution at least a 10-percent interest (as defined in §6038(e)(3)(C)); or
2. The $100,000 test — the value of the property contributed, added to the value of any other property contributed in a §721 contribution by that person (or a related person) during the 12-month period ending on the date of the transfer, exceeds $100,000.

Category 3 also captures two related situations: a §721(c) gain-deferral contribution of built-in-gain property to a partnership with related foreign partners (Treas. Reg. §1.721(c)-6, reported through the gain-deferral schedules), and a later disposition by the partnership of previously contributed property that the US person had to report, while that person remains a partner (Treas. Reg. §1.6038B-2(a)(4)).

Example. USP A contributes property worth $150,000 to FP B in exchange for a partnership interest. Even if A's resulting interest is small, the contribution exceeds the $100,000 12-month threshold, so A is a Category 3 filer and reports the transfer on Schedule O of Form 8865. (A would also be Category 3 on the other test if the contribution left A with a 10%-or-greater interest — either test, on its own, is enough.)

This is the partnership analog of the outbound-transfer reporting that §6038B(a)(1)(A) requires for property transferred to a foreign corporation (reported on Form 926, and often paired with a §351 disclosure). Same statute, different subparagraph: a contribution to a foreign partnership routes to Form 8865 Schedule O, not Form 926.

Category 4 — a reportable event (§6046A)

A US person who has a reportable event under §6046A during the person's tax year is a Category 4 filer. The statute lists three kinds of event:

Any United States person … (1) who acquires any interest in a foreign partnership, (2) who disposes of any portion of his interest in a foreign partnership, or (3) whose proportional interest in a foreign partnership changes substantially, shall file a return.

— IRC §6046A(a)

Section 6046A applies only where the US person holds at least a 10-percent interest (directly or indirectly) before or after the event; the regulations then measure each reportable event by the person's direct interest, against the 10% line (Treas. Reg. §1.6046A-1(b)(1)):

• Acquisition — the person did not own a 10%-or-greater direct interest and, as a result of the acquisition, does (e.g., 8% → 12%); or the person's direct interest increased by at least a 10-percent interest since the last reportable event (e.g., 11% → 21%).
• Disposition — the person owned a 10%-or-greater direct interest and, as a result of the disposition, owns less than 10% (e.g., 12% → 8%); or the direct interest decreased by at least a 10-percent interest since the last reportable event.
• Change in proportional interest — the person's direct proportional interest increased or decreased by at least the equivalent of a 10-percent interest (for example, from a co-partner's withdrawal).

Example. USP A's direct interest in FP B rises from 8% to 12% during the year. A did not previously own a 10%-or-greater interest and now does, so the acquisition is a reportable event — A is a Category 4 filer and reports it on Schedule P of Form 8865.

The §6046A and §6038B reporting overlap: if a US person acquires a 10%-or-greater interest through a §721 contribution that is properly reported under §6038B (Category 3), the same acquisition is not separately reported under §6046A — but it sets the direct-interest baseline for testing future Category 4 events (Treas. Reg. §1.6046A-1(f)(1)).

A determination framework

Worked in this order, the categories resolve cleanly:

1. Classify the entity. Confirm it is a foreign partnership (not a corporation → Form 5471, not a disregarded entity → Form 8858). Check default classification and any Form 8832 election.
2. Attribute ownership. For each US person, compute the interest in the partnership after §267(c) attribution — including from siblings and other family — measured by capital, profits, and deductions/losses.
3. Test control (Category 1). Does any US person own more than a 50% interest (any of the three measures)? Each one is a Category 1 filer.
4. If there is no Category 1 filer, test Category 2. Did a US person own ≥10% while US persons each owning ≥10% together owned >50% (distinct, non-overlapping interests)? Each is a Category 2 filer. (If a Category 1 filer exists, skip — Category 2 is suppressed.)
5. Test contributions (Category 3). Did the US person contribute property in a §721 transfer with a ≥10% post-contribution interest, or >$100,000 of property in the trailing 12 months (counting related persons)?
6. Test reportable events (Category 4). Did the US person's direct interest cross the 10% line — up or down — or change proportionally by ≥10 points?
7. Assign every category that applies, and map each filer to its schedule set.

In plain terms the answer is a per-person, per-partnership, per-year matrix, not a single yes/no. Build the ownership picture first — with family and entity attribution, across capital, profits, and losses — then read the categories off it, remembering that a single Category 1 controller switches Category 2 off for everyone. This determination — who files, in which category, with which schedules, and the authority for each — is exactly what PILOT produces from a client's ownership facts.

Exceptions and relief

• Multiple Category 1 filers (Treas. Reg. §1.6038-3(c)(1)). If more than one US person is a controlling fifty-percent partner of the same partnership for the same year, only one Form 8865 need be filed, containing all the information each would have reported. Priority goes to a partner controlling capital or profits — a person who is a controlling fifty-percent partner only by reason of a deductions-or-losses allocation may file the single return only if there is no US person who controls via capital or profits. Each non-filing Category 1 partner attaches a "Controlled Foreign Partnership Reporting" statement to its own return. Because PILOT cannot know whether the partners will coordinate, the relieved partner's obligation stays in place until the joint filing actually covers it (unconfirmed relief is not relief).
• Constructive-owner exception (Treas. Reg. §1.6038-3(c)(2)). A US person who owns no direct interest and is a Category 1 or 2 filer solely by §267(c) attribution from another US person is excused if that other US person files (or is itself a covered constructive owner, or a single return is filed under the multiple-Category-1 exception). This is a true elimination, not just a single-filer convenience.
• Affiliated group filing a consolidated return (Treas. Reg. §1.6038-3(c)(3)). The common parent may file one Form 8865 on behalf of all group members required to report.
• §761 election out of subchapter K (Treas. Reg. §1.6038-3(e)). A partnership that has validly elected out of all of subchapter K under §1.761-2 is outside this reporting requirement.
• State and local government employee retirement trusts are not required to report (Treas. Reg. §1.6038-3(d); §1.6038B-2(b)).

Example — two controllers, one filer. USP A owns more than 50% of FP B's capital; USP D, on the same facts, is allocated more than 50% of FP B's losses. Both are controlling fifty-percent partners, so both are Category 1 filers. Under the multiple-Category-1 exception, only one Form 8865 need be filed — and priority goes to A (the capital/profits controller); D, who controls only through a loss allocation, may not be the single filer while A exists. D instead attaches a "Controlled Foreign Partnership Reporting" statement to its return. The obligation stays on D until A's Form 8865 actually covers it.

A note on the schedules

Form 8865 carries different schedules by category, but the schedules are downstream of the threshold question this guide answers. In outline: Category 1 files the full set (the income statement, balance sheet, partners' capital, Schedule K/K-1, and the Schedule K-2/K-3 international items); Category 2 files a reduced set (including Schedule K-1 and K-3 for its own interest); Category 3 files Schedule O (the §6038B transfer report); and Category 4 files Schedule P (the §6046A acquisitions, dispositions, and changes report). Where the foreign partnership itself files a Form 1065 for the year, Category 1 and 2 filers may substitute the corresponding Form 1065 schedules.

Penalties for getting it wrong

• Categories 1 and 2 (§6038). $10,000 per partnership per year for failure to furnish the required information; if the failure continues more than 90 days after IRS notice, an additional $10,000 for each 30-day period, capped at $50,000. Plus a §6038(c) reduction of the foreign tax credit, with further reductions for continued failure.
• Category 3 (§6038B). A penalty equal to 10% of the fair market value of the contributed property, capped at $100,000 unless the failure is due to intentional disregard (§6038B(c)(1), (c)(3)). The transferor must also recognize gain on the contribution as if the property had been sold for its fair market value. A reasonable-cause exception applies (§6038B(c)(2)).
• Category 4 (§6046A). A $10,000 penalty under §6679 for failing to report a reportable event, with the same continuation mechanic (an additional $10,000 per 30-day period after notice, capped at $50,000).
• §6501(c)(8). The assessment statute of limitations for the return generally does not begin until the required information is furnished — so an unfiled Form 8865 can hold the year open.
• Criminal exposure (§§7203, 7206, 7207) is possible for willful failures.

These figures are statutory dollar amounts, not inflation-indexed (unlike the FBAR penalties). PILOT flags whether a contribution crosses the $100,000 Category 3 threshold as a single yes/no — it never computes the 10%-of-value penalty or the gain on the contribution; that is downstream work for the engagement's tax professional.

What recent law changed (and what it did not)

Form 8865's tests are not affected by the headline 2025 international change. The One Big Beautiful Bill Act (OBBBA, Pub. L. 119-21) §70353 restored §958(b)(4) for foreign-corporation tax years beginning after December 31, 2025 — which reshapes CFC status and therefore Form 5471. But Form 8865's control and interest tests run on §6038(e)(3) and §267(c), and its contribution and event tests on §6038B and §6046A — none of which incorporates §958(b). A restoration of the §958(b)(4) downward-attribution limit does not move the Form 8865 answer. (Watch the boundary in mixed structures: the same engagement can have a Form 5471 conclusion that shifts for 2026 while the Form 8865 conclusion does not.)

Two genuine currency points do apply to Category 3: the §721(c) gain-deferral regime (final regulations effective for contributions on or after January 18, 2017) governs contributions of built-in-gain property to partnerships with related foreign partners; and Treas. Reg. §1.6038-3 was amended (paragraphs (g)(3) and (g)(4)) to add §267A hybrid and §250 FDII information for the Category 1 schedule set in recent years.

Relationships to other regimes and forms

Form 8865 rarely sits alone. The questions on either side of it decide whether it applies — and what else applies with it.

• Classification points the analysis. The same facts that make Form 8865 apply (a foreign partnership) would, on a different classification, point elsewhere: a foreign corporation to Form 5471, a foreign disregarded entity to Form 8858, a 25%-foreign-owned US entity to Form 5472. Run the §301.7701-2/-3 classification before anything else.
• The outbound-transfer parallel. A Category 3 contribution is the partnership sibling of the §6038B(a)(1)(A) outbound transfer to a foreign corporation (reported on Form 926, often with a §351 disclosure). A single property transfer for foreign equity can be a reportable transfer under one regime or the other depending on whether the recipient is a corporation or a partnership.
• PFIC stock inside the partnership. If the foreign partnership owns stock of a foreign corporation that is a passive foreign investment company, a US partner can have a Form 8621 obligation flowing through the partnership — the partnership's own filing does not make that disappear. See Who must file Form 8621, and is the foreign company a PFIC?.
• Foreign-asset disclosure. An interest in a foreign partnership is a specified foreign financial asset for Form 8938, and the partnership's foreign accounts can drive an FBAR — though Form 8938's duplicative-reporting rule lets an interest already reported on Form 8865 be identified on Part IV rather than re-detailed. See FBAR vs Form 8938: who files which, and how do they differ?.
• K-2 / K-3. Category 1 and 2 filers carry the partnership's international items on Schedule K-2/K-3 through the Form 8865.

In plain terms the same foreign venture can put a client on Form 8865, Form 8938, an FBAR, and — if there is PFIC stock inside it — Form 8621, all at once. And one classification call decides whether the venture is even an 8865 question or a 5471 one. Run them together for the engagement; PILOT determines, for each client, which of these forms is required and why.

What Form 8865 is not

Form 8865 reports — it does not compute your client's tax. The partner's distributive share, any §721(c) gain, the foreign tax credit, and any inclusion that travels through the partnership are separate downstream work that builds on the facts the form captures. The first question — and the one this guide answers — is simply whether a Form 8865 obligation exists, for whom, and in which category.