K-1 Tax Form: Reading the Boxes, Loss Limits, and QBI

A K-1 tax form is the statement a partnership, S corporation, estate, or trust sends you each year showing your share of the entity’s income, losses, deductions, and credits — figures you then carry onto your own Form 1040. You get one because the entity itself generally doesn’t pay federal income tax. Instead, the tax items pass through to the owners or beneficiaries, and you owe tax on your share whether or not the entity actually distributed cash to you. Every box on the K-1 maps to a specific line on your personal return, and misreading a single entry can mean overpaying or triggering an IRS notice.

Which Version of the K-1 You Received

There isn’t one universal K-1. The form comes in three versions, each tied to a different entity return, and the tax treatment turns on which one landed in your mailbox.

Partnership K-1 From Form 1065

Partnerships send this version to general partners, limited partners, and LLC members. The entity files Form 1065 with the IRS and allocates each partner a share of everything the partnership earned, lost, or deducted. That allocation follows the partnership agreement, not necessarily an equal split.¹

The big distinction here is self-employment tax. If you’re a general partner who actively works in the business, your ordinary business income and guaranteed payments are typically subject to the combined 15.3% self-employment tax rate (Social Security at 12.4% plus Medicare at 2.9%). Limited partners generally owe self-employment tax only on guaranteed payments for services, not on their share of ordinary business income, though this area has been heavily litigated and the line between “limited” and “general” for SE tax purposes isn’t always obvious.²

S Corporation K-1 From Form 1120-S

S corporations send this version to shareholders. The entity files Form 1120-S, and each shareholder’s K-1 reports a pro rata share of income based strictly on stock ownership. Unlike partnerships, S corporations can’t specially allocate income to certain owners.³

Shareholders generally don’t owe self-employment tax on S corporation K-1 income. The tradeoff is that any shareholder who works in the business must take a reasonable salary reported on a W-2, with standard payroll taxes withheld. The IRS can reclassify distributions as wages if the salary is unreasonably low.⁴⁵

Estate and Trust K-1 From Form 1041

Estates and trusts send this version to beneficiaries. The fiduciary files Form 1041 and reports your share of any income the entity distributed or was required to distribute. Income the trust or estate keeps is taxed at the entity level, often at steep rates, since trusts hit the top bracket at relatively low income levels.⁶

Income keeps its original character when it passes through. Qualified dividends stay qualified dividends. Long-term capital gains remain long-term. That matters because those income types get preferential tax rates on your personal return.⁷

Reading the Income Boxes

Each version has its own box layout, but the partnership K-1 is the most detailed and the most common. The box numbers below refer to the partnership form unless noted. S corporation and estate/trust K-1s use different numbering for some items, but the concepts are the same.

Ordinary Business Income or Loss (Box 1)

Box 1 is your share of the entity’s net profit or loss from its core operations. On a partnership K-1, this amount may be subject to self-employment tax if you’re a general partner who materially participates. On an S corporation K-1, Box 1 flows to Schedule E without triggering self-employment tax.⁸

A loss in Box 1 isn’t automatically deductible. It must clear four separate limitations before you can use it. More on those below.

Guaranteed Payments (Boxes 4a, 4b, 4c)

Guaranteed payments appear only on partnership K-1s. Box 4a reports payments for services, Box 4b reports payments for use of capital, and Box 4c is the total. These payments function like a salary. The partnership owes them regardless of whether it turned a profit, and payments for services are nearly always subject to self-employment tax.⁹

Net Rental Real Estate Income or Loss (Box 2)

Box 2 reports your share of income or loss from the entity’s rental real estate. This income is generally treated as passive, which means losses here can only offset other passive income unless you qualify for the $25,000 rental loss allowance or meet the real estate professional standard.

Interest, Dividends, and Royalties (Boxes 5 Through 7)

Box 5 is interest, Box 6a is ordinary dividends, Box 6b is qualified dividends (taxed at preferential long-term capital gains rates), and Box 7 is royalties. These get combined with any interest and dividends you received directly on your own 1099 forms.⁹

Capital Gains and Losses (Boxes 8 Through 10)

The K-1 breaks capital transactions into several categories, and getting the boxes right matters because each flows to a different line on Schedule D:

Box 8: net short-term capital gain or loss (assets held one year or less), taxed at ordinary income rates.
Box 9a: net long-term capital gain or loss (assets held longer than one year), taxed at preferential rates.
Box 9b: collectibles gain, taxed at a maximum 28% rate.
Box 9c: unrecaptured Section 1250 gain, taxed at a maximum 25% rate.
Box 10: net Section 1231 gain or loss from the sale of business property held longer than one year.

All of these flow to Schedule D and combine with any capital transactions from your personal brokerage accounts.¹⁰

Self-Employment Earnings (Box 14, Partnership Only)

Box 14 tells you the amount subject to self-employment tax, generally the sum of your ordinary business income from Box 1 and guaranteed payments for services from Box 4a. This figure transfers to Schedule SE, where you calculate the actual tax. Half of the resulting self-employment tax is deductible as an adjustment to income on your Form 1040.²

Deductions, Credits, and the QBI Deduction

Section 179 Deduction

The Section 179 deduction lets you immediately write off the cost of qualifying business equipment instead of depreciating it over several years. On a partnership K-1 it appears in Box 12; on an S corporation K-1 it appears in Box 11.⁹¹¹

For 2026, the maximum Section 179 deduction is $2,560,000, and it begins phasing out dollar-for-dollar once the entity places more than $4,090,000 of qualifying property in service. Your share from the K-1 combines with any Section 179 amounts from other sources on Form 4562. The total can’t exceed your aggregate taxable income from all active businesses; unused amounts carry forward.

Charitable Contributions

Your share of cash charitable donations made by a partnership is reported in Box 13, Code A. The entity doesn’t deduct these itself. You claim them on your own Schedule A as itemized deductions, subject to the same AGI-based percentage limits that apply to personal charitable giving.¹²

The Section 199A Qualified Business Income Deduction

One of the most valuable items on a K-1 is the data you need to claim the Section 199A deduction, which can knock up to 20% off your qualified business income from partnerships and S corporations. This information appears in Box 20, Code Z on partnership K-1s and Box 17, Code V on S corporation K-1s. Instead of a single dollar figure, you’ll often see “STMT” in the box, pointing to an attached statement with detailed breakdowns.¹³

That statement gives you the pieces to complete Form 8995 (simplified) or Form 8995-A (full version): your share of qualified business income, the entity’s W-2 wages, and the unadjusted basis of qualified property. At higher income levels, the deduction phases out for specified service businesses like law, accounting, health care, and consulting. For 2025, the phase-out begins at $197,300 for single filers and $394,600 for joint filers, adjusted annually for inflation.¹⁴

Don’t overlook this one. Many K-1 recipients miss the deduction because the data isn’t in a prominently labeled box. It’s buried in an attachment. If your K-1 includes a Section 199A statement, make sure you or your preparer are using it.

Four Loss Limitations You Need to Clear

A loss on your K-1 doesn’t automatically reduce your taxable income. Before you can deduct it, the loss must survive four separate tests, applied in this specific order. If the loss gets blocked at any stage, it’s suspended rather than lost, and carries forward to future years when conditions change.

Basis Limitation

You can only deduct losses up to your tax basis in the entity. Your basis starts with what you invested (cash or property contributed) and is adjusted each year: increased by income and additional contributions, decreased by losses, deductions, and distributions. If a loss exceeds your basis, the excess is suspended until your basis is restored, typically through future income allocations or additional contributions.¹⁵

S corporation shareholders who claim a loss, receive a distribution, or dispose of stock must file Form 7203 to show basis supports the deduction.¹⁶

At-Risk Limitation

Losses that survive the basis test must then pass the at-risk rules. You’re “at risk” for amounts you’ve invested plus amounts you’ve personally borrowed for use in the activity. You’re generally not at risk for nonrecourse loans (debt where you’re not personally liable), with an important exception for qualified nonrecourse financing secured by real property. This test prevents deducting losses backed by money you could walk away from without consequence.

Passive Activity Loss Rules

Losses that clear the at-risk hurdle face the passive activity rules. Income and losses are either passive (from activities you don’t materially participate in) or non-passive. Passive losses can only offset passive income. They can’t reduce your wages, interest, or other non-passive income.

One significant exception exists for rental real estate. If you actively participate in managing a rental property (making decisions about tenants, repairs, and lease terms), you can deduct up to $25,000 of rental losses against non-passive income. This allowance phases out by $1 for every $2 your modified adjusted gross income exceeds $100,000, disappearing entirely at $150,000.¹⁷

Taxpayers who qualify as real estate professionals (spending more than 750 hours per year in real property trades or businesses and materially participating in each rental) can treat rental losses as non-passive, sidestepping this limitation.

Excess Business Loss Limitation

Any loss that survives the first three tests faces one final cap. For 2026, you can’t deduct business losses exceeding $256,000 (single) or $512,000 (joint) against non-business income like wages or investment gains. Amounts above this threshold become a net operating loss carryforward to the following year.

The 3.8% Net Investment Income Tax

K-1 income that qualifies as net investment income — rental income, interest, dividends, capital gains, and income from passive business activities — may trigger an additional 3.8% tax. This Net Investment Income Tax applies when your modified adjusted gross income exceeds $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately). These thresholds are set by statute and are not adjusted for inflation.¹⁸

The tax is calculated on Form 8960 and equals 3.8% of the lesser of your net investment income or the amount by which your MAGI exceeds the threshold. Income from a business you materially participate in is generally excluded, so ordinary business income from Box 1 of a partnership where you actively work wouldn’t be hit. That same income would be subject to NIIT if you’re a passive investor.

Where the Numbers Go on Your 1040

Most K-1 business income lands on Schedule E, Part II. You’ll list each K-1 separately with the entity’s name, EIN, and type. Box 1 ordinary business income flows into the income or loss column. Net rental real estate income from Box 2 goes to Schedule E, Part I, alongside any rental properties you own personally. The combined result from both parts flows to your Form 1040.¹⁵

Interest from Box 5 and ordinary dividends from Box 6a go on Schedule B, blending with amounts from your personal 1099s. Qualified dividends from Box 6b are used to calculate your preferential tax rate. Capital gains and losses from Boxes 8 through 10 go to Schedule D. Charitable contributions go on Schedule A if you itemize. Section 179 amounts pass through Form 4562 before flowing to Schedule E. Partnership self-employment earnings from Box 14 go to Schedule SE.¹⁰

Tracking Your Tax Basis

Your tax basis is essentially your running investment balance in the entity. It starts with your initial contribution, increases with income allocations and additional contributions, and decreases with loss deductions and distributions. Keeping accurate records isn’t optional. Basis determines whether losses are deductible, whether distributions are tax-free returns of capital or taxable income, and what gain or loss you recognize when you eventually sell your interest.

For S corporation shareholders, the IRS formalized this with Form 7203. Attach it to your return whenever you claim a loss, receive a non-dividend distribution, or sell any of your stock.¹⁶ Partnership basis tracking doesn’t have a dedicated IRS form, but the consequences of getting it wrong are identical. If you can’t prove basis, the IRS can deny your losses.

When Your K-1 Arrives Late

Partnerships and S corporations must file their returns and furnish K-1s to owners by the 15th day of the third month after the entity’s tax year ends, so March 15 for calendar-year entities.¹⁹ In practice, many entities file for an automatic six-month extension using Form 7004. When that happens, you might not receive your K-1 until September.

A late K-1 almost always means extending your own return. File Form 4868 by April 15 to get an automatic six-month extension, pushing your filing deadline to October 15. The extension only grants more time to file, not more time to pay. You still owe interest on any tax not paid by April 15, and you may owe a late-payment penalty of 0.5% per month on the unpaid balance.²⁰

To avoid underpayment penalties, pay at least 90% of your actual 2026 tax liability by April 15. Alternatively, meet the safe harbor by paying 100% of the tax shown on your 2025 return, or 110% if your 2025 adjusted gross income exceeded $150,000 ($75,000 if married filing separately).²¹ When you’re waiting on a K-1, the prior-year safe harbor is usually the more practical route. You know that number, and meeting it protects you from penalties regardless of what the K-1 eventually shows.

Corrected K-1s and Disagreements

If a corrected K-1 arrives after you’ve filed, you’ll generally need to file Form 1040-X. Enter your original figures in Column A, the changes in Column B, and the corrected amounts in Column C. Attach the corrected K-1 and any affected schedules. Amended returns typically take 8 to 12 weeks to process.²²

If you believe the amounts on your K-1 are wrong and the entity refuses to correct them, you have two options. You can report the K-1 as issued and wait for the entity to sort things out, or you can report the amounts you believe are correct and attach Form 8082 (Notice of Inconsistent Treatment) explaining the discrepancy: which K-1 line you disagree with, what the entity reported, what you’re reporting instead, and why.²³ Filing Form 8082 puts the IRS on notice that you and the entity don’t agree, which protects you from penalties for inconsistent reporting. Reporting inconsistent amounts without Form 8082 can trigger an automatic assessment.

Foreign Items and Schedule K-3

If the entity has foreign income, foreign taxes paid, or foreign partners, you may receive Schedule K-3 alongside your K-1. The K-3 provides the detail you need to claim foreign tax credits, report foreign-source income, and complete other international tax forms.²⁴ If your K-1 has an amount in Box 16 (indicating a K-3 is attached) or Box 21 (foreign taxes paid), account for those items. Ignoring a K-3 can mean leaving foreign tax credits on the table or failing to report required international information.

1
Internal Revenue Service. Instructions for Form 1065 (2025) – Section: Schedules K and K-1
2
Internal Revenue Service. Instructions for Form 1065 (2025) – Section: Net Earnings From Self-Employment
3
Internal Revenue Service. Instructions for Form 1120-S (2025) – Section: Shareholders Pro Rata Share Items
4
Internal Revenue Service. S Corporation Employees, Shareholders and Corporate Officers
5
Internal Revenue Service. S Corporation Compensation and Medical Insurance Issues
6
Internal Revenue Service. Instructions for Form 1041 and Schedules A, B, G, J, and K-1 (2025) – Section: Schedule K-1
7
Internal Revenue Service. 2025 Instructions for Schedule K-1 (Form 1041) for a Beneficiary Filing Form 1040 or 1040-SR
8
Internal Revenue Service. 2025 Partners Instructions for Schedule K-1 (Form 1065) – Section: Box 1
9
Internal Revenue Service. Schedule K-1 (Form 1065) 2025
10
Internal Revenue Service. Partners Instructions for Schedule K-1 (Form 1065) (2025) – Section: Income (Loss)
11
Internal Revenue Service. 2025 Schedule K-1 (Form 1120-S)
12
Internal Revenue Service. 2025 Instructions for Form 1065 – Section: Line 13a Cash Contributions
13
Internal Revenue Service. Shareholders Instructions for Schedule K-1 (Form 1120-S) – Section: Box 17 Code V
14
Internal Revenue Service. Instructions for Form 8995 (2025)
15
Internal Revenue Service. 2025 Partners Instructions for Schedule K-1 (Form 1065)
16
Internal Revenue Service. Instructions for Form 7203
17
Office of the Law Revision Counsel. 26 USC 469 – Passive Activity Losses and Credits Limited
18
Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax
19
Internal Revenue Service. Publication 509 (2026), Tax Calendars
20
Internal Revenue Service. Form 4868 – Application for Automatic Extension of Time To File U.S. Individual Income Tax Return
21
Internal Revenue Service. 2026 Form 1040-ES (NR) Instructions
22
Internal Revenue Service. Instructions for Form 1040-X (Rev. December 2025)
23
Internal Revenue Service. Instructions for Form 8082 (Rev. October 2025)
24
Internal Revenue Service. Form 1065, Schedules K-2 and K-3 Filing Requirements