A K-1 from a partnership is the tax document that tells you, and the IRS, your share of the partnership’s income, deductions, and credits for the year. Formally called Schedule K-1 (Form 1065), it exists because a partnership doesn’t pay federal income tax itself. The law is direct on this point: “A partnership as such shall not be subject to the income tax imposed by this chapter.”1Office of the Law Revision Counsel. 26 USC 701 – Partners, Not Partnership, Subject to Tax The business files an information return, Form 1065, and every partner gets a K-1 showing their slice.2Internal Revenue Service. About Form 1065, US Return of Partnership Income Those numbers then get folded into your personal Form 1040.
Here is the part that catches new partners off guard: you owe tax on your share of the partnership’s income whether or not any cash actually reaches you. If your share of profit is $80,000 and the partnership reinvests every dollar, you still report $80,000 and pay tax on it. Setting money aside during the year is not optional.
What the Form Shows
Schedule K-1 has three parts. Skim each one when the form arrives, because errors are easier to fix before you file than after.
Part I identifies the partnership — legal name, Employer Identification Number, and entity type. The information must match what appears on Form 1065. A mismatched EIN can generate IRS notices on its own.3Internal Revenue Service. Instructions for Form 1065
Part II is about you. It shows your beginning and ending ownership percentages for profit, loss, and capital, breaks your share of partnership liabilities into recourse debt (where you’re personally on the hook) and nonrecourse debt (where the lender’s only recourse is the collateral), and reports your capital account. Compare the percentages here against your signed partnership agreement — discrepancies happen more often than you’d expect.
Part III is where the money is. Each line uses an alphanumeric code to report a specific item: ordinary business income, rental income, interest, dividends, capital gains, Section 179 expense, foreign tax credits, and so on. Each code maps to a specific line on your personal return, and the IRS cross-references its copy of your K-1 against what you file. Coding errors are one of the most common triggers for automated notices.
If you spot a mistake on the K-1, ask the partnership to issue a corrected version to both you and the IRS.
Your Distributive Share and Guaranteed Payments
Your “distributive share” is the portion of the partnership’s income, gains, losses, deductions, and credits allocated to you. It’s set by the partnership agreement, or, if the agreement is silent or the allocation doesn’t have substantial economic effect, by your overall interest in the partnership.4Office of the Law Revision Counsel. 26 USC 704 – Partners Distributive Share
Some partners also receive guaranteed payments: compensation for services or for the use of capital, paid regardless of whether the partnership turned a profit. The tax code treats guaranteed payments as if they were made to an outsider. The partnership deducts them as a business expense, and you report them as ordinary income.5Office of the Law Revision Counsel. 26 USC 707 – Transactions Between Partner and Partnership
Self-employment tax treatment depends on your role. General partners generally owe self-employment tax on both their distributive share and any guaranteed payments.6Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) Limited partners generally owe self-employment tax only on guaranteed payments for services, not on their distributive share of partnership income.7Internal Revenue Service. Entities 1
Three Limits on Deducting Partnership Losses
A loss on your K-1 does not automatically reduce your taxable income. Partnership losses have to clear three tests, applied in this order. Any loss that fails a test gets suspended and carried forward until the test can be met.
Basis
You can deduct losses only up to your basis in the partnership. Basis starts with what you contributed — cash or the adjusted value of property — and moves each year: up for your share of income, down for distributions and losses claimed.8Office of the Law Revision Counsel. 26 USC 705 – Determination of Basis of Partners Interest Your share of partnership liabilities feeds into basis as well, which is why the recourse/nonrecourse split in Part II matters. When basis hits zero, further losses are suspended.
At-Risk
Even with basis, you can only deduct losses to the extent you are personally at risk. You’re at risk for money and property you contributed and for borrowed amounts you’re personally liable for or have secured with non-activity property.9Office of the Law Revision Counsel. 26 USC 465 – Deductions Limited to Amount at Risk Nonrecourse loans where you have no personal exposure generally don’t count, with a narrow exception for qualified nonrecourse financing secured by real property.
Passive Activity
If you don’t materially participate in the partnership’s business — meaning your involvement isn’t regular, continuous, and substantial — your share of the loss is passive, and passive losses can only offset passive income, not wages or investment income.10Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited Limited partnership interests are generally treated as passive regardless of the hours you put in. Unused passive losses carry forward and are fully released when you dispose of your entire interest in the partnership.
The tests stack. A $100,000 loss might clear the basis test, get partially blocked by the at-risk rules, and have the remainder frozen as passive. Tracking all three is tedious; skipping the exercise is how partners end up with IRS adjustments years later.
Getting the K-1 onto Your Return
Most partnership income and losses land on Schedule E (Supplemental Income and Loss), which attaches to Form 1040.11Internal Revenue Service. About Schedule E (Form 1040), Supplemental Income and Loss Self-employment income flows to Schedule SE. Capital gains and losses go to Schedule D. Specialized items such as foreign tax credits may require additional forms. The Schedule K-1 instructions list each code and where it belongs.12Internal Revenue Service. Partners Instructions for Schedule K-1 (Form 1065)
Deadlines
Calendar-year partnerships must file Form 1065 and deliver K-1s to partners by March 15.13Internal Revenue Service. Publication 509 (2026), Tax Calendars Your personal return is then due April 15.14Internal Revenue Service. IRS Announces First Day of 2026 Filing Season A partnership can request an automatic six-month extension using Form 7004, moving its deadline to September 15.15Internal Revenue Service. Instructions for Form 7004 If the partnership extends, you’ll likely need to extend your personal return too, because you can’t accurately file without the K-1.
Estimated Tax Payments
Nobody withholds income tax from your partnership share, so the IRS expects quarterly estimated payments. You generally need to pay estimates if you expect to owe $1,000 or more when you file.16Internal Revenue Service. Estimated Taxes Payments are due in April, June, September, and the following January. To avoid an underpayment penalty, pay at least 90% of your current-year tax or 100% of last year’s tax, whichever is smaller. Partners who join a profitable partnership mid-year sometimes get surprised by a large estimated payment due only weeks after their income starts.
Penalties
Penalties hit at two levels. For tax year 2026, a partnership that files Form 1065 late owes $255 per partner for each month or partial month the return is late, up to 12 months.17Internal Revenue Service. Failure to File Penalty A ten-partner partnership that files three months late is looking at $7,650 before anyone examines the tax itself.
Separate penalties apply for failing to furnish correct K-1s to partners on time: $60 per K-1 if corrected within 30 days, $130 if corrected by August 1, and $340 per K-1 after that. Intentional disregard raises it to $680 per statement.18Internal Revenue Service. Information Return Penalties
At the partner level, leaving K-1 income off your personal return can bring accuracy-related penalties, interest running from the original due date, and audit exposure. The IRS matches K-1 data to individual returns automatically, so unreported partnership income rarely stays hidden.
Not the Only Kind of K-1
The partnership K-1 (Form 1065) is the most common, but two other schedules share the name. S corporations issue Schedule K-1 (Form 1120-S) to shareholders, and estates and trusts issue Schedule K-1 (Form 1041) to beneficiaries. The tax treatment differs in ways that matter — most notably, S corporation K-1 income is generally not subject to self-employment tax, while a general partner’s share on a Form 1065 K-1 typically is. If you receive more than one type, keep them separated, because the numbers flow to different lines and carry different rules.