Do you need to file a 1040X with form 8379?

Yes, if you are filing Form 8379 (Injured Spouse Allocation) to request a portion of your tax refund that was used to pay your spouse's past debts, you generally need to file Form 1040X (Amended U.S. Individual Income Tax Return) if your original return requires changes. This is necessary to amend your tax return and to include the allocation of the refund. Make sure to follow the specific instructions for both forms to ensure proper processing.