What is a Schedule K-1?

Partnerships (Form 1065), S corporations (Form 1120-S) and estates and trusts (Form 1041) generally don't pay income tax themselves. Instead, each owner or beneficiary receives a Schedule K-1 showing their share of the entity's results, which they report on their own return.

K-1s are a frequent reason individual returns wait. They can only be prepared after the entity's own return, so they often arrive late in tax season, and corrected K-1s are common.

Firms usually plan for this by asking which clients expect K-1s, setting realistic due dates for those clients, and deciding early whether an extension is likely.

Free resource: Client tax document checklist.