K-1
Schedule K-1 is a US tax form issued by partnerships (Form 1065), S-corporations (Form 1120-S), and estates / trusts (Form 1041) to report each owner's or beneficiary's share of the entity's income, deductions, credits, and other tax items. The recipient reports the K-1 amounts on their individual tax return.
K-1 income is pass-through income — the entity itself doesn't pay federal income tax (with limited exceptions); instead, the income flows through to the owners and is taxed at their individual rates. This contrasts with C-corporation income, which is taxed at the entity level and then again when distributed as dividends.
K-1 timing creates planning friction. K-1s are typically issued in March or April for the prior tax year — often after the recipient has already filed their personal tax return. Recipients of multiple K-1s commonly file an extension because they cannot complete their personal return until all K-1s arrive. The information on the K-1 may include items that affect cost basis, capital account, or at-risk amounts that the recipient must track over time.
For financial planning, K-1 income is treated differently from W-2 wages in several contexts. Mortgage underwriting often applies haircuts to K-1 income for stability. Quarterly estimated tax payments may be required since no withholding is taken at the entity level. Solo 401(k) and SEP-IRA contribution limits are computed against K-1 distributions plus reasonable salary (for S-Corps) — a calculation that differs by entity type.
Synthetic households with K-1-producing assets (private equity, real-estate partnerships, family LLCs, S-corps) need full per-K-1 detail: entity name, EIN, box-by-box values (ordinary business income, rental income, interest, dividends, capital gains, §1231 gains, foreign income, AMT preferences), and capital-account roll-forward (beginning balance, contributions, distributions, ending balance). The capital-account history is what auditors and engines actually need to compute at-risk basis on an eventual disposition.
Common pitfalls
- Treating Box 1 (ordinary business income) as the only meaningful number — Boxes 2 (real estate), 5 (interest), 6 (dividends), 9 (capital gains), and 11 (other) all carry separate tax characters that get aggregated wrongly when collapsed.
- Ignoring §469 passive-activity rules — losses on K-1s from passive activities can be deferred or non-deductible against active income.
- Missing the at-risk basis ledger — a K-1 partner can't deduct losses below their at-risk amount, which is recomputed annually from contributions and prior-year allocations.
- Filing the personal return before all K-1s arrive — extension is usually the right move, not estimating K-1 numbers.
Examples
Investor receives a K-1 from a real-estate LP showing Box 2 (rental income) of $40,000, Box 8 (LT capital gain) of $15,000 from a property sale, Box 11A (other portfolio income) $2,000 from interest, Box 13W (other deductions) $3,500 of investment management fee. The $40k rental and $2k interest are ordinary income; the $15k LT gain is preferential rate. Aggregating to a single 'K-1 income' line of $53,500 mis-characterizes ~$15k.