Yes my husband and I are not living together and filling seperate why do i need his ssn

[macuser_22 · Accepted solution]

Because the tax law requires it.   If one spouse on a separate return itemizes deductions then both must itemize, even if one spouse has nothing to itemize - that spouse cannot take the standard deduction.

To prevent spouses from doing just that to "game" the system, the IRS will match separate returns using the other spouses SSN that must be on each separate return to insure that both spouses are following the tax law..