I had Social Security income of 10500 in 2021 and a short term capital gain of 1900 do I need to file a federal return?

[MayaD]

No, you don't need to file a return.

Your benefits may be taxable if the total of (1) one-half of your benefits, plus (2) all of your other income, including tax-exempt interest, is greater than the base amount for your filing status.

The base amount for your filing status is:

• $25,000 if you're single, head of household, or qualifying widow(er),
• $25,000 if you're married filing separately and lived apart from your spouse for the entire year,
• $32,000 if you're married filing jointly,
• $0 if you're married filing separately and lived with your spouse at any time during the tax year.

[Critter-3]

Sorry but you may have to file ... it depends on the GROSS sales amount and not just the net gain.  You can use one of the 8 FREE FILE OPTIONS available at https://www.irs.gov/filing/free-file-do-your-federal-taxes-for-free to know for sure if you are required to file even if you will not get a refund or owe taxes.