You must file separately for each year, and years prior to 2018 can only be done by mail.
If you file Form 8379 separately, please be sure to attach a copy of all Forms W-2 and W-2G for both spouses, and any Forms 1099 showing federal income tax withholding, to Form 8379. The processing of Form 8379 may be delayed if these forms are not attached, if the form is incomplete when filed, or if you attach a copy of your joint tax return.