I am not allowed to submit my return because it says there is a duplicate social security number. What can I do to solve this?

[xmasbaby0]

If there is a duplicate SSN you cannot fix it and e-file.   You have to print, sign and mail your return.   There is no way to beat a duplicate SSN problem and e-file.   The IRS will sort it out.  Eventually you will receive a letter about the duplicate SSN.

[fanfare]

you can check your SSN numbers for typos (not uncommon)

If you claim dependents you can check with family members who may have used that SSN already,

then you'd have to take that person off, or file on paper with the SSN if you dispute that.