This is confusing because the IRS in redesigning the 1040 moved a fair number of lines to other schedules, in this case, Schedules 2 and 3.
So now, the 1040 form has to ask you for the calculated tax on line 11a and then adds to this the other taxes on Schedule 2 to make line 11.
Ditto with line 12a: the original Child Tax Credit is on line 12a, and all the other credits are imported from Schedule 3.
In detail:
Here are the IRS instructions on what goes into line 11a:
• Tax on your taxable income. Figure the tax using one of the methods described, later.
• Tax from Form(s) 8814 (relating to the election to report child's interest or dividends). Check the appropriate box.
• Tax from Form 4972 (relating to lump-sum distributions). Check the appropriate box.
• Tax due to making a section 962 election (the election made by a domestic shareholder of a controlled foreign corporation to be taxed at corporate rates). See section 962 for details. Check box 3 and enter the amount and “962” in the space next to that box. Attach a statement showing how you figured the tax.
• Recapture of an education credit. You may owe this tax if you claimed an education credit in an earlier year, and either tax-free educational assistance or a refund of qualified expenses was received in 2018 for the student. See Form 8863 for more details. Check box 3 and enter the amount and “ECR” in the space next to that box.
• Any tax from Form 8621, line 16e, relating to a section 1291 fund. Check box 3 and enter the amount of the tax and “1291TAX” in the space next to that box.
• Repayment of any excess advance payments of the health coverage tax credit from Form 8885. Check box 3 and enter the amount of the repayment and “HCTC” in the space next to that box.
• Net tax liability deferred under section 965(i). If you have a deferred net 965 tax liability under section 965(i), check box 3 and enter (as a negative number) the amount of the deferred net 965 tax liability and “965” on the line next to that box.
• Triggering event under section 965(i). If you had a triggering event under section 965(i) during the year and did not enter into a transfer agreement, check box 3 and enter the amount of the triggered deferred net 965 tax liability and enter “965INC” on the line next to the box.
Note that line 11 is the sum of 11a plus any amount from Schedule 2 (Form 1040).
Line 12a is from the 2018 Child Tax Credit and Credit for Other Dependents Worksheet in the 1040 Instructions. It is what you would think of as the credit.
Line 12 is the sum of line 12a and any non-refundable credits from Schedule 3.
