If your federal return is rejected due to Error Code F1040-511 or F1040SSPR-511, then the primary taxpayer is already listed as Spouse on a previously filed return with filing status Married Filing Separately. 

If one of the spouses already filed using Married Filing Separately as the filing status, the other spouse cannot file a separate return using a filing status of Single, Married Filing Jointly, or Qualifying Widower. 

You will need to review and correct your SSN and Filing Status entries in the Basic Info section of the program, then repeat the filing steps to resubmit your return.