If you received a Schedule K-1, you have a share of income, deductions, or losses from a partnership, S-corporation, trust, or estate. The K-1 is not a standalone document you enter on one line. Each box flows to a specific schedule on Form 1040, and the rules around self-employment tax, basis, and passive losses make this one of the more complex forms individual taxpayers encounter.
Who Issues a Schedule K-1?
Three types of entities issue K-1s, each on a different form:
- Partnerships (Form 1065): Each partner receives a K-1 showing their allocated share of income, deductions, and credits.
- S-Corporations (Form 1120-S): Each shareholder receives a K-1 with their pro-rata share of S-corp items.
- Trusts and Estates (Form 1041): Beneficiaries receive a K-1 for income distributed or required to be included in their gross income.
Where Does K-1 Income Flow on Form 1040?
K-1 income is not a single entry. Each box maps to a different schedule:
- Box 1 (ordinary business income/loss): Schedule E, Part II
- Box 2 (net rental real estate income/loss): Schedule E, Part II (subject to passive activity rules under IRC Section 469)
- Box 4 (partnership guaranteed payments): Schedule E, Part II; also subject to self-employment tax
- Box 5 (interest income): Schedule B
- Capital gains and losses (short-term and long-term): Schedule D (box numbers differ between Form 1065 and Form 1120-S; see the instructions for your specific K-1)
- Net Section 1231 gain or loss: Form 4797, then carried to Schedule D
Importing your K-1 into tax software will handle most of this routing automatically, but you should verify each item lands in the correct place, particularly capital gains, rental losses, and guaranteed payments.
Partnership K-1 vs. S-Corp K-1: Key Differences
These two K-1 types look similar but carry very different tax consequences, particularly for self-employment tax and basis calculation.
What Limits Your Ability to Deduct a K-1 Loss?
A K-1 loss is not automatically deductible. Four hurdles apply in this order:
1. Basis limitation (IRC Sections 704(d) and 1366(d))
You cannot deduct losses beyond your basis. For a partnership, your outside basis starts with your capital contribution, increases by your share of income and entity-level debt, and decreases by distributions and loss allocations. For an S-corp, your stock basis works similarly, but debt basis exists only for direct shareholder loans to the corporation. Losses exceeding basis are suspended and carry forward indefinitely.
2. At-risk limitation (IRC Section 465)
Even with sufficient basis, losses are limited to the amount you are economically at risk. Third-party nonrecourse debt generally does not increase your at-risk amount, even if it increases your partnership basis.
3. Passive activity limitation (IRC Section 469)
If you are a limited partner or a non-material participant in an S-corp, losses are passive and can only offset other passive income. See our passive activity loss rules guide for the material participation tests and the $25,000 rental allowance.
4. Excess business loss limitation (IRC Section 461(l))
The One Big Beautiful Bill Act (signed July 4, 2025) made this limitation permanent for tax years beginning after December 31, 2025. If your total losses from all business activities exceed your business income plus approximately $313,000 (single) or $626,000 (MFJ), the excess is disallowed and converted to an NOL carryforward rather than a current-year deduction.
Work through these four hurdles in order. A loss that clears the basis test can still be disallowed at each successive layer.
When Do K-1s Arrive?
K-1s often arrive much later than W-2s and 1099s:
- Partnership K-1s (Form 1065): Due March 15. If the partnership files an extension, K-1s may not arrive until September 15.
- S-Corp K-1s (Form 1120-S): Same deadlines as partnerships, March 15 or September 15 on extension.
- Trust and Estate K-1s (Form 1041): Due April 15, or September 30 if the trust files an extension.
If you are waiting on a K-1 from a partnership that typically extends, filing your own extension (Form 4868) gives you until October 15 to file your personal return and prevents late-filing penalties while you wait.
Have questions about your Schedule K-1 or pass-through entity taxes? Contact TS CPA for a free consultation. We respond within the same day.