Q. Is there a way to find out?
A. Look at line 28 of form 1040.
$2000 per kid is the maximum you get. Only people who do not get the full $2000 Child Tax Credit (CTC) get any Additional Child Tax Credit (ACTC). So, since you were given 4k child tax credit for your 2 kids, you do not get any ACTC, at all. Line 28 of form 1040 will be blank.
Full explanation
The child tax credit (CTC) is limited to your tax liability. The CTC is a non-refundable credit and can only reduce your income tax to 0, It can not help you beyond eliminating your tax liability. But, if you have more than $2500 of earned income, some or all of it is usually given back to you thru the "Additional Child tax credit". That is, part of the CTC may be on line 28 of form 1040 (2021- 2024) instead of line 19. The ACTC is calculated on form 8812 and is basically 15% of your earned income over $2500. The ACTC is only the difference between $2000 and the amount of CTC on line 19. But, is a maximum of $1700 (2024).
