And it's not for FICA, it's only for Social Security in box 4. Add up your box 4s and separately your spouse box4 (If Married).
If you had more than one employer and the total of box 4 (only box 4 not box 6) on all your 2019 W2s for Social Security is more than $8,239.80 (max 132,900 wages) you get the excess back on your tax return. And it is for each spouse separately, not combined. Check 1040 Schedule 3 line 11 for it. Then Schedule 3 goes to 1040 line 18d.
