You Not need to file another injured spouse form for the Stimulus check. If you already filed your 2019 taxes with this 8379 Injured Spouse form you are all set. The Economic Stimulus Q & A on the IRS website states this.
Therefore, when you get the letter from the Treasury offset department stating that your portion of the Stimulus was taking for your spouses back child support, it will tell you to fill out an injured spouse form to get your portion back. But if you already filed The Injured Spouse with your 2019 you do not have to do it again.
