I need to refill 2020 taxes. SS# corrected with SSA. It's corrected. 2021 taxes no problem. Do I still need to do a 1040X or can I just send in 2020's Tax forms?

1040x otherwise there mat be issues since you will have filed two returns with different ssns

Thanx,

Original 2020 had correct SS#, but SSA had incorrect number.  Had to send birth certificated, government ID and correspondence with letter head confirming ID to SSA to correct their numbers.

Doyour12345

if you listed SS benefits on 1040 there's no reason to amend.

If you're 2020 return was rejected because the social security number was incorrect and you never filed the 2020 return by mail then you need to mail in a 2020 return now. Do not mail in an amended return if the original was never filed.