@suraky Line 23400 less Line 23500 equals Line 23600. So, if your spouse didn't have any social benefit repayments, then Line 23400 is the same as Line 23600. Otherwise, you can see Line 23400 on the PDF Preview or Archive of your spouse/partner's return. Alternatively, you can prepare your returns together with your spouse/partner so the software can see that info automatically.
Previous years of TurboTax Online didn't ask for Line 23400, only Line 23600.
@thoss
If you want to edit the info you entered for your spouse/partner, click on "2024 tax Return" at the top left of the page. Then click on Tax Profile, then Additional Information About Your Spouse. Click Continue until you get to the "Tell us more about SPOUSE" page. There you can edit what you entered for line 23600 & 23500.
