If you are self-employed, you will need to report your net earnings to Social Security and the Internal Revenue Service (IRS). Net earnings for Social Security are your gross earnings from your trade or business, minus all of your allowable business deductions and depreciation.
In figuring your net earnings for Social Security, don’t include the following:
You must complete the following federal tax forms by April 15 following any year in which you have net earnings of $400 or more:
You can download these forms from the IRS Forms, Instructions & Publications website.
Even if you don't owe any income tax, you must complete Form 1040 and Schedule SE to pay self-employment Social Security tax. This is true even if you already get Social Security benefits.