Does she have any other income besides SSD? If she only gets SS or SSDI or a SSA-1099 it is not taxable and she doesn't have to file a return. Where is it saying she owes? Check the actual 1040 or 1040-SR line 37 is a tax due. Does she have any taxable income on 1040 line 15? Any other kind of tax on lines 17-23?