Is K-1 income subject to self-employment tax?

Generally yes on a partnership K-1 for a general partner, where the distributive share of trade or business income flows to Schedule SE. Generally no on an S corporation K-1, where the shareholder pays payroll tax on their reasonable salary instead. That difference is the core of the S corporation planning case.

What is a guaranteed payment on a partnership K-1?

A guaranteed payment is compensation to a partner determined without regard to partnership income, reported in box 4 of a 1065 K-1. It is deductible to the partnership and ordinary income to the partner, and it is generally subject to self-employment tax. S corporation K-1s have no equivalent because owners take a W-2 salary instead.

Why does my K-1 show income I never received?

Pass-through entities allocate income to owners whether or not cash was distributed. You are taxed on your allocated share, not on what hit your bank account. A profitable business that reinvests everything still produces taxable K-1 income for its owners, which is why distributions for taxes are negotiated in advance.

How does basis differ between an S corporation and a partnership?

Partnership basis includes a share of entity liabilities, so debt increases the amount of loss a partner can deduct. S corporation stock basis does not include entity-level debt; only direct shareholder loans to the corporation create debt basis. This is the single most consequential technical difference between the two forms.

When do I receive my K-1?

Both partnership and S corporation returns are due March 15 for calendar-year entities, with a six month extension available to September 15. Because many entities extend, K-1s frequently arrive after the individual April deadline, which is why K-1 recipients often extend their own returns as a matter of routine.

IRS Form Guide

K-1: 1120-S vs 1065

Two forms with the same name and materially different consequences. Self-employment tax, basis, and debt all behave differently depending on which one arrives.

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01The Structural Differences 02Box by Box Comparison 03Basis, Debt, and Deductible Losses 04What to Do When Your K-1 Arrives 05Frequently Asked Questions

Schedule K-1 Hub>1120-S vs 1065

Written by Bryan Martin, CPA, Managing Partner and Founder of Taxstra. Last updated August 15, 2026.

Quick answer

A 1120-S K-1 reports an S corporation shareholder's share; a 1065 K-1 reports a partner's share. The partnership version adds guaranteed payments and a share of entity liabilities. Partnership trade or business income is generally subject to self-employment tax; S corporation K-1 income generally is not.

Both forms are called Schedule K-1 and both report a pass-through owner's share of entity activity. That is where the similarity ends. The box numbering differs, the partnership version reports items the S corporation version has no concept of, and the tax consequences diverge in ways that routinely surprise owners who have held both.

The two differences that matter most are self-employment tax and basis. Everything else is detail.

The Structural Differences

Four divergences that drive real dollars.

	1065 K-1, partnership	1120-S K-1, S corporation
Self-employment tax	Generally applies to a general partner's trade or business share	Generally does not apply; payroll tax runs through W-2 salary instead
Owner compensation	Guaranteed payments, reported on the K-1	W-2 wages, reported separately from the K-1
Share of entity debt	Reported and included in basis	Not reported and not included in stock basis
Allocation flexibility	Special allocations permitted with substantial economic effect	Strictly pro rata by share ownership
Ownership restrictions	Few; entities and foreign partners permitted	Limited shareholder count, one class of stock, eligibility rules

Why the self-employment difference drives entity choice

An S corporation owner pays payroll tax only on a reasonable salary, while the remaining profit passes through free of self-employment tax. A general partner pays self-employment tax on the entire distributive share. On a profitable business, that single distinction is the substance of the S corporation election argument.

Box by Box Comparison

Where the same information lives on each form.

Item	1065 K-1	1120-S K-1
Ordinary business income	Box 1	Box 1
Net rental real estate income	Box 2	Box 2
Guaranteed payments	Box 4	No equivalent
Interest income	Box 5	Box 4
Section 179 deduction	Box 12	Box 11
Self-employment earnings	Box 14	No equivalent
Qualified business income data	Box 20, code Z	Box 17, code V
Share of liabilities	Part II, item K	Not reported

Taxstra CPA Tip

Taxstra Tip

The qualified business income codes, box 20 code Z on a partnership K-1 and box 17 code V on an S corporation K-1, carry the wage and property figures needed to compute the deduction at higher income levels. When those attachments are missing or incomplete, the deduction is frequently understated. Ask the entity for the supporting statement rather than accepting a blank.

Basis, Debt, and Deductible Losses

The technical difference with the largest dollar consequence.

You can only deduct losses up to your basis. Partnerships and S corporations calculate that limit very differently, and the difference determines whether a leveraged business generates usable deductions.

Worked example

You contribute $50,000 to a business that borrows $400,000 and generates a $150,000 loss allocated to you in year one.

As a partnership

Basis includes your share of the debtLoss deductible

As an S corporation

Stock basis is $50,000; entity debt does not count$100,000 suspended

Illustrative only, ignoring at-risk and passive activity limits which apply on top. The suspended loss is not lost, but it does not reduce this year's tax.

Watch Out

Loans to the corporation are not the same as guarantees

An S corporation shareholder creates debt basis only by lending money directly to the corporation. Personally guaranteeing a bank loan to the corporation does not create basis, despite putting the shareholder on the hook economically. This distinction has been litigated repeatedly and consistently resolved against taxpayers.

Because basis is calculated by the owner rather than the entity, and because entities do not always track it, reconstructing basis years later during a sale is a common and expensive exercise. The practice of tracking it annually is covered in the owner basis guide.

What to Do When Your K-1 Arrives

Four checks before it goes into your return.

Check the ownership percentages in Part II

Confirm they match your understanding of the deal. Errors here propagate through every allocated number on the form.

Read every attached statement

Coded boxes reference supplemental schedules that carry the detail. A K-1 without its attachments is incomplete and cannot be entered correctly.

Reconcile the capital account rollforward

Beginning balance, contributions, income, distributions, and ending balance should tie. A break usually indicates an entity-level error worth resolving before filing.

Expect to extend your own return

Entities that extend to September deliver K-1s after the individual April deadline. Extending is routine for K-1 recipients, not a sign that anything is wrong.

The entity side of the partnership version is covered in the Form 1065 guide, and the general anatomy of a K-1 is in the Schedule K-1 overview. Professional service partners should read the partner tax guide, real estate investors should start with entity selection, and anyone considering restructuring should look at the buy-in and buy-out guide alongside the LLC filing overview. For owners eventually selling the business, the business sale guide explains why basis tracking matters long before the exit.

Receiving a K-1 You Do Not Fully Understand?

Box 17 and box 20 codes carry basis limits, at-risk limits, and passive activity consequences that most software handles poorly. A Taxstra CPA will read it properly. The initial consultation is free.

Frequently Asked Questions

A 1120-S K-1 comes from an S corporation and a 1065 K-1 comes from a partnership. The box numbering differs, partnership K-1s report guaranteed payments and a share of liabilities that S corporation K-1s do not, and the basis and self-employment tax consequences are substantially different.

The Entity Choice Matters More Than the Form

Partnership versus S corporation drives self-employment tax, basis, and how much you can actually deduct. That decision is worth far more than reading the K-1 correctly. Book a free initial consultation.

Next Steps

Filing it yourself is fine. Optimizing it is where the money is.

Getting the form right keeps you out of trouble. The strategies below are what actually lower the bill.

Want a CPA to run the numbers for you?

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Authoritative Sources

Citations reflect U.S. federal tax law as of the article's last reviewed date.

Related Pass-Through Entity Guides

Form 1065 Explained

The partnership return, its deadline, and the per-partner late penalty.

Owner Basis Management

Tracking basis before you need it, rather than reconstructing it at exit.

Law Firm Partner Taxes

Guaranteed payments, quarterly estimates, and equity partner mechanics.

LLC Tax Filing

How an LLC is actually taxed, and which return it owes.