Hello @sasuga !
As a self employed person, you have likely always filed Form 1040, and included a Schedule C for your self employment income and expenses.
Now that you have retired, if you are no longer receiving income from that business or incurring expenses, you don't need to do anything different other than not file that Schedule C, and instead include retirement income from sources such as social security in the proper place on Form 1040. If you tell TurboTax what kind of income you have, you will be guided right along the way.
One caveat: if this is the first year you will not be operating your business, you may need to indicate that you have stopped operating your business on your tax return. Return to the self employment section of the return as always, and be sure to check the box that says "I stopped (my business) in 2021." TurboTax will help you handle any tax implications from the ceasing of operations, including disposition of business assets or converting assets to personal use.
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