Per IRS Instructions for Form 8379, page 1:
Are you an Injured Spouse? You may be an injured spouse if you file a joint return and all or part of your portion of the overpayment was, or is expected to be, applied (offset) to your spouse's legally enforceable past-due federal tax, state income tax, state unemployment compensation debts, child support, or a federal nontax debt, such as a student loan.
How to File 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 return.
Time Needed To Process Form 8379 Generally, if you file Form 8379 with a joint return on paper, the time needed to process it is about 14 weeks (11 weeks if filed electronically). If you file Form 8379 by itself after a joint return has been processed, the time needed is about 8 weeks.
Where to File If you file Form 8379 by itself after you filed your original joint return electronically, then mail Form 8379 to the Internal Revenue Service Center for the area where you live.*
To complete Form 8379 in the TaxAct® program:
The TaxAct program does not support Form 8857, Request for Innocent Spouse Relief.
Per IRS Instructions for Form 8857, page 1:
If you believe, taking into account all the facts and circumstances, only your spouse or former spouse should be held responsible for all or part of the tax, you should request relief from the tax liability, including related penalties and interest. To request relief, you must file Form 8857.
Line 1 Complete line 1 to determine if you should file Form 8857.
Whether you check "Yes" or "No," you should go to line 2 (discussed next) to find out if you should file another form (Form 8379) to request injured spouse relief. Injured spouse relief is different from innocent spouse relief and you cannot request it by filing Form 8857. You must file Form 8379. For example, if you check "Yes" on line 1 and "Yes" on line 2, you will have to file both Forms 8857 and 8379.
Line 2 Complete line 2 to determine if you should file Form 8379.
Check "Yes" for any tax year to which all of the following apply.
If all three of the above apply, you may be able to get back your share of the refund for that tax year if you file Form 8379, Injured Spouse Allocation.
If you checked "Yes" on line 1, and all three of the above do not apply, check "No" and go to line 3.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.