W-2 Efile Upload
Efiling your W-2s on the SSA website requires you to change the extension of the W-2 file produced by C21. After you create the file in Payroll/Electronic Filing/W-2s, look for the file that ends in .FED in your C21/data/CompanyName folder. Right-click and change the ending to .txt. You can then upload your file to the SSA site.