A K-1 is a tax form used by partnerships to provide investors with detailed information on their share of a partnership’s taxable income. Partnerships are generally not subject to federal or state income tax, but instead issue a K-1 to each investor to report his or her share of the partnership’s income, gains, losses, deductions and credits. The K-1s are provided to investors on an annual basis so that each investor can include K-1 amounts on his or her tax return.