You cannot e-file an injured spouse form (Form 8379) by itself, separately from your tax return. If you are filing Form 8379 by itself you have to print it, sign it, and file it by mail. Send it by a service that will give you confirmation of delivery, such as certified mail with a return receipt.
If you are filing Form 8379 by itself, note the following from the IRS Instructions for Form 8379.
"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 previously filed joint tax return."
Because of the Covid-19 pandemic, the IRS is currently not processing forms that are filed by mail. When they start to process them again they will have reduced staff and a big backlog, so it will be quite a while before your injured spouse claim is processed.
See the IRS Instructions for Form 8379 for the address to mail your injured spouse form to. If it says to mail it to the Internal Revenue Service Center for the area where you live, you can find the address at the following link on the IRS web site. Use the address for returns that do not have a payment enclosed.
Where to File Paper Tax Returns With or Without a Payment
