To report Schedule K-1 income on your tax return, transfer each numbered box from the K-1 to the matching line or schedule on your Form 1040 — most items flow to Schedule E, Part II, with interest and dividends going to Schedule B, capital gains to Schedule D, and self-employment earnings to Schedule SE. You keep the K-1 itself in your records; you don’t attach it to your return. Before you deduct any loss shown on the form, you also need to run it through three separate limitation tests.
The specifics depend on which K-1 you received, so start there.
Which K-1 Do You Have
Three pass-through entities issue Schedule K-1, and the box numbers don’t all line up.1Legal Information Institute. Pass-Through Taxation
- Schedule K-1 (Form 1065) comes from partnerships and most multi-member LLCs.2Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income
- Schedule K-1 (Form 1120-S) comes from S corporations. The box layout closely mirrors the partnership version, but shareholders track basis on Form 7203 rather than through the liability categories on the partnership form.3Internal Revenue Service. Instructions for Form 1120-S (2025)4Internal Revenue Service. Form 7203 S Corporation Shareholder Stock and Debt Basis Limitations
- Schedule K-1 (Form 1041) comes from estates and trusts. Its box numbers don’t correspond to the other two, and it carries unique items like an estate tax deduction for income in respect of a decedent in Box 10 and excess deductions on termination in Box 11.5Internal Revenue Service. Instructions for Schedule K-1 (Form 1041) for a Beneficiary Filing Form 1040 or 1040-SR
The walkthrough below uses the partnership K-1, which is the most common. If you have the S-corp or trust version, the concepts carry over, but check your version’s instructions for box-number differences before you start entering numbers.
Where Each Box Goes on Your 1040
Part III of the partnership K-1 is where the money lives. Each numbered box maps to a specific spot on your personal return.6Internal Revenue Service. Schedule K-1 (Form 1065) 2025
Box 1 — Ordinary business income or loss. Goes on Schedule E, Part II. This is the entity’s net profit or loss from regular operations.
Box 2 — Net rental real estate income or loss. Also flows to Schedule E, but rental activity is generally treated as passive under Section 469, so losses usually can’t offset wages or business income.7Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited There is a narrow exception: if you actively participate and your modified adjusted gross income is $100,000 or less, you can deduct up to $25,000 in rental losses against non-passive income. The allowance phases out completely at $150,000.8Internal Revenue Service. 2025 Instructions for Form 8582 – Passive Activity Loss Limitations
Box 5 — Interest income. Form 1040, line 2b (through Schedule B if required).9Internal Revenue Service. 2025 Partners Instructions for Schedule K-1 (Form 1065)
Boxes 6a and 6b — Dividends. Box 6a is ordinary dividends; Box 6b breaks out the qualified portion, which is taxed at the lower capital gains rates.
Boxes 8 and 9a — Capital gains. Box 8 holds net short-term gains (held one year or less), taxed at ordinary rates. Box 9a holds net long-term gains, taxed at 0%, 15%, or 20% depending on your total taxable income.10Internal Revenue Service. Topic No. 409, Capital Gains and Losses Both flow to Schedule D. If your modified adjusted gross income exceeds $200,000 single or $250,000 married filing jointly, these gains may also be subject to the 3.8% Net Investment Income Tax.11Internal Revenue Service. Topic No. 559, Net Investment Income Tax
Box 12 — Section 179 deduction. Your share of the entity’s election to expense qualifying property. Calculate any personal-level limitation on Form 4562. If the property later drops below 50% business use, part of the deduction gets recaptured.12Office of the Law Revision Counsel. 26 U.S. Code 179 – Election to Expense Certain Depreciable Business Assets
Box 14 — Self-employment earnings. Flows to Schedule SE if you’re a general partner. Self-employment tax runs 15.3% (12.4% Social Security plus 2.9% Medicare).13Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) Your partner classification in Part II of the K-1 controls whether Box 14 applies. General partners typically owe self-employment tax on their distributive share; limited partners generally owe it only on guaranteed payments for services.14Internal Revenue Service. Instructions for Schedule SE (Form 1040) (2025)
Box 15 — Credits. Tax credits passing through from the entity, including credits for low-income housing and research activities. These reduce your tax dollar-for-dollar.
Box 20 — Other information. A catch-all box with coded items. Code Z is the one that matters most for many filers, because it carries the data for the Section 199A deduction.
The Section 199A Deduction from Box 20 Code Z
If the partnership runs an active trade or business, Code Z gives you the qualified business income figures for a Section 199A deduction of up to 20% of that income. Use Form 8995 for the simplified calculation or Form 8995-A when limitations apply.15Internal Revenue Service. Instructions for Form 8995 (2025)
The math is straightforward when your taxable income stays below roughly $201,750 single or $403,500 married filing jointly for 2026. Above those thresholds, W-2 wage and property limitations kick in. If your business is in a specified service field (law, accounting, consulting, medicine, and similar), the deduction phases out entirely above about $276,750 single or $553,500 married filing jointly. The K-1 should include the data you need; your job is to move it to the right form.
Loss Limitations Before You Deduct
A loss on your K-1 doesn’t automatically land on your return. Three tests apply in sequence, and a loss must clear all three.
Basis
You can only deduct losses up to your basis in the entity. For a partnership, basis is your capital contributions plus your share of entity liabilities (Item K on the K-1, split into nonrecourse, qualified nonrecourse, and recourse categories) minus distributions.9Internal Revenue Service. 2025 Partners Instructions for Schedule K-1 (Form 1065) For an S-corp shareholder, basis lives on Form 7203 and includes stock basis plus direct loans to the company, but not your share of entity-level debt.4Internal Revenue Service. Form 7203 S Corporation Shareholder Stock and Debt Basis Limitations Anything above basis is suspended and carried forward.
At-Risk
Even with enough basis, the at-risk rules can further restrict the deduction. You’re at risk for cash contributed, property pledged, and borrowed amounts you’re personally liable to repay. Nonrecourse debt from unrelated lenders generally doesn’t count, with a narrow exception for certain real estate financing. Report the limitation on Form 6198.16Internal Revenue Service. Instructions for Form 6198
Passive Activity
Losses that clear the first two tests still face Section 469. If you don’t materially participate in the business, the loss is passive and can only offset passive income, not wages or portfolio income. Rental activity is generally passive regardless of participation, subject to the $25,000 allowance noted earlier. Track the limitation on Form 8582.8Internal Revenue Service. 2025 Instructions for Form 8582 – Passive Activity Loss Limitations
Losses blocked at any stage aren’t lost. They carry forward and can be used in a future year when your basis grows, your at-risk amount grows, or you generate passive income to absorb them.
Do Not Attach the K-1 to Your Return
The IRS instructions are explicit: keep your Schedule K-1 for your records and do not file it with your Form 1040 unless you’re specifically required to — for example, when Box 15, Code O reports backup withholding.17Internal Revenue Service. Partners Instructions for Schedule K-1 (Form 1065) (2025) The partnership files a copy with the IRS when it submits Form 1065, so the agency already has your numbers. Your job is to transfer them accurately.
Most filers use tax software or a preparer to e-file, which feeds the K-1 data straight into the return. Electronically filed returns are generally processed within 21 days; paper returns can take substantially longer.18Internal Revenue Service. Processing Status for Tax Forms19Internal Revenue Service. Why It May Take Longer Than 21 Days for Some Taxpayers to Receive Their Federal Refund
Estimated Tax Payments
K-1 income has no withholding, so you’re expected to make quarterly estimated payments. The safe harbor: pay at least 90% of the current year’s tax or 100% of last year’s (110% if your prior-year adjusted gross income exceeded $150,000).20Internal Revenue Service. Estimated Tax Because you often won’t know the K-1 amounts until well after year-end, many filers lean on the prior-year safe harbor to avoid penalties when income spikes.
When the K-1 Is Late, Missing, or Wrong
Calendar-year partnerships and S corporations must issue K-1s by March 15, or September 15 if the entity extended. In practice, many arrive later, and there’s no way to force the entity to speed up.
If your K-1 hasn’t arrived by April 15, file Form 4868 for an automatic six-month extension to October 15.21Internal Revenue Service. Application for Automatic Extension of Time to File U.S. Individual Income Tax Return The extension is for filing, not for paying. If you expect to owe, send a payment with the extension to limit interest.
If it still hasn’t arrived by your extended deadline, file using reasonable estimates. When your estimated figures differ from what the entity ultimately files, attach Form 8082 to flag the inconsistency. Form 8082 is also the correct filing if you believe an amount on your K-1 is wrong and you want to report the item differently than the entity did.22Internal Revenue Service. Instructions for Form 8082
Corrected K-1s show up sometimes after you’ve already filed. If the new numbers change your tax, file Form 1040-X for the affected year, attach updated versions of any changed schedules (typically Schedule E, and possibly Schedule D or SE), and explain the change in Part II.23Internal Revenue Service. Instructions for Form 1040-X Amended Individual Income Tax Return
If Foreign Items Are Involved: Schedule K-3
If the partnership has foreign income, foreign taxes paid, or other international items, you may also receive Schedule K-3 alongside your K-1. It provides the detail you need for foreign tax credits and other international calculations.24Internal Revenue Service. Form 1065, Schedules K-2 and K-3 Filing Requirements Small partnerships meeting the domestic filing exception (receipts under $250,000, assets under $1 million, timely K-1 delivery, and no Schedule M-3 requirement) can skip K-3 unless a partner requests it.
If the Numbers Don’t Match: CP2000
The IRS runs automated matching between the income on your 1040 and the K-1 data the entity filed. When those don’t line up, you’ll get a CP2000 notice proposing adjustments.25Internal Revenue Service. Understanding Your CP2000 Series Notice Most CP2000s trace back to a transposed number or a corrected K-1 that arrived after filing. Respond promptly with documentation and the issue usually clears without penalty.