The Schedule K-1 is an Internal Revenue Service (IRS) tax form issued annually for an investment in partnership interests. The purpose of the Schedule K-1 is to report each partner's share of the partnership's earnings, losses, deductions, and credits. It serves a similar purpose for tax reporting as one of the various Forms 1099, which report dividend or interest from securities or income from the sale of securities.

The Schedule K-1 is also used by shareholders of S corporations, companies of under 100 stockholders that are taxed as partnerships. Trusts and estates that have distributed income to beneficiaries also file Schedule K-1s.

While a partnership itself is generally not subject to income tax, individual partners (including limited partners) are liable to be taxed on their share of the partnership income, whether or not it's distributed. A K-1 is commonly issued to taxpayers who have invested in limited partnerships (LPs) and some exchange-traded funds (ETFs), such as those that invest in commodities.

1:04

Schedule K-1

How a Schedule K-1 Works

The tax code in the United States allows the use of certain pass-through taxation, which shifts tax liability from an entity (like a partnership) to the individuals who have an interest in it. Hence, the presence of the Schedule K-1: It requires the partnership to track each partner's basis (that is, the degree of financial participation) in the enterprise. A partnership prepares a K-1 to get a sense of what each partner's share of the returns is, based on the amount of capital he has in the partnership. A partner’s basis is increased by capital contributions and his share of income, while it is reduced by a partner’s share of losses and any withdrawals.

The financial information posted to each partner’s Schedule K-1 is sent to the IRS along with Form 1065. S Corporations also file K-1s, accompanying them with Form 1120S.

The K-1: a Notoriously Tardy Tax Form

While not filed with an individual partner’s tax return, the Schedule K-1 is necessary for a partner to accurately determine how much income to report for the year. Unfortunately, the K-1 tends to have a reputation for being late; required to be received by March 15 (or the 15th day of the third month after the entity's tax year ends), in fact, it's often one of the last tax documents to be received by the taxpayer. There are numerous reasons why, but the most common is the complexity of calculating partners' shares, and that every partner's K-1 often has to be individually figured. (It used to be worse: Before the IRS rules changed in 2017, K-1s didn't have to be received until April 15.)

To add insult to the injurious wait, the Schedule K-1 can be quite complex and require multiple entries on the taxpayer's federal return, including such entries on the Schedule A, Schedule B, Schedule D and, in some cases, Form 678. That's because a partner can earn several types of income on Schedule K-1, including rental income from a partnership’s real estate holdings and income from bond interest and stock dividends. It's also possible that K-1 income can trigger the alternative minimum tax.