Partnership Taxes in Plain Terms, Form 1065 and the K-1

A partnership does not pay federal income tax. It files a return, Form 1065, whose only real purpose is to produce a Schedule K-1 for every partner, and the K-1 is what actually lands on each partner's personal return. Miss the filing and the bill is not interest on tax owed, since the partnership owes none; it is a flat penalty of $255 per partner, per month late, for up to 12 months, assessed against the partnership regardless of whether it made a dollar of profit (IRS, 2025 Form 1065 instructions). A four-partner firm that files eight months late owes $8,160 for a return that may report a loss.

That penalty exists because the IRS has nothing else to go on until the K-1s arrive: no entity-level return means no entity-level tax to chase, so the only leverage is a penalty keyed to how many K-1s were held up. What follows is the calendar, the K-1's own contents, and the basis rule that decides whether money coming out of the partnership is ever taxed twice. This is general information, not a substitute for a preparer who sees the actual return; a partnership with anything unusual on it should have one.

A K-1 is long, but three boxes do most of the work for an owner who is not a tax preparer. Box 1 is ordinary business income (or loss), the core number a partner's share of a successful year amounts to. Box 14 carries the self-employment earnings information that decides what, if anything, a partner owes in self-employment tax on top of income tax; a partner who also has a guaranteed payment for services sees that figure folded in here. Box 19 reports distributions: cash or property the partnership actually paid out during the year, which is a separate question from how much income the partner was allocated.

That separation between income allocated and cash distributed is the single most common source of confusion in a small partnership. A partner can owe tax on a K-1's Box 1 income in a year when the partnership distributed nothing at all, because the partnership kept the cash to grow the business. The K-1 reports what was earned, not what was paid out, and the two numbers are only the same by coincidence.

Every partner has a basis in the partnership interest, separate from the capital account the K-1 reports, and basis is what stands between a distribution and a tax bill. Under section 731(a), a partner does not recognize gain on a cash distribution from the partnership except to the extent the cash distributed exceeds that partner's adjusted basis immediately before the distribution; the excess is taxed as a capital gain, as if the partner had sold part of the interest.

Basis starts at what the partner contributed, goes up each year by the partner's share of income (the Box 1 figure above, among others), and goes down by distributions and by the partner's share of losses. A partner who has been allocated several years of income without taking matching distributions is building up basis that absorbs a later large payout tax-free; a partner who takes distributions faster than income is allocated is drawing basis down toward zero, and the next dollar out after that is a capital gain. Since Schedule K-1 Item L already requires the partnership to report capital accounts on a tax-basis method, the number partners need for this comparison should already be in front of them each year; it is worth checking rather than assuming.

None of this changes how a partner is paid day to day, which runs on a separate set of rules covered in how business partners pay themselves: guaranteed payments, draws and distributive share are taxed differently from each other even though all three eventually show up somewhere on the K-1. The capital account that basis tracking depends on is worth understanding in its own right, line by line, rather than only at tax time; the steps for setting up the structure that produces all of this in the first place are in how to start a business partnership.