Schedule K-1(Form 1065) is Partner's Share of Income, Deductions, Credits, etc.
Specifically, a partnership files Form 1065 (U.S. Return of Partnership Income). Each partner's share of income, etc., is reported on Schedule K-1. The information on Schedule K-1 is entered on Schedule C (Profit or Loss from Business). From Schedule C it's entered on line 12 Business Income or (Loss) on Form 1040. Schedule K-1 isn't attached to Form 1040. You keep it for your records.