I've been trying to file my taxes, but I keep getting a message saying a file has already been submitted with my SS#, but I haven't filed.

[VolvoGirl]

It could also be if you signed up on the IRS non-filer tool to give the IRS your Direct Deposit Info for the Stimulus Check.  If you did then see

https://ttlc.intuit.com/community/tax-topics/help/stimulus-how-to-file-your-return-after-getting-rej...

[Anonymous]

if you did not use the non-filers tool, then someone else put your SSN on their tax return. the procedure outlined in the link still applies except do not write Amended EIP Return at the top.  if you believe you were the victim of identity theft also include form 14039 with the federal return.