21 — Total Credits Updated for tax year 2025

What this line means

The sum of your Child Tax Credit (line 19) and Schedule 3 nonrefundable credits (line 20). This total is subtracted from your tax before credits (line 18) to get your tax after credits on line 22. Total credits cannot exceed your total tax — they reduce your tax to zero but never below it. Any excess disappears (for nonrefundable credits) or moves to the refundable credit lines later on the return.

Does this apply to you?

• Every filer with amounts on line 19 or line 20 completes this line
• This is a simple addition: line 19 plus line 20
• If you only have the Child Tax Credit and no Schedule 3 credits, line 21 equals line 19

Easy to overlook

Nonrefundable credits are “use it or lose it” If your total credits on line 21 exceed your tax on line 18, the excess nonrefundable credits vanish. They do not carry forward to next year (with a few exceptions like the residential energy credit). This is why filers with low tax liability sometimes get less benefit from credits like the Lifetime Learning Credit or Saver’s Credit than they expected. ¹ [SOURCE: General filing pattern — nonrefundable credits limited to tax liability]

Refundable credits are on different lines The credits on line 21 are all nonrefundable — they stop at zero tax. Refundable credits like the Earned Income Credit (line 27a), Additional Child Tax Credit (line 28), and American Opportunity Credit (line 29) appear later in the payments section and can generate a refund even if your tax is zero. ² [SOURCE: IRS Form 1040 instructions — Line 21 computation]

Watch out for this

Assuming a large total credit means a large refund. Nonrefundable credits only reduce your tax liability. If your tax before credits is $3,000 and your total credits are $5,000, you get $3,000 of benefit (tax reduced to zero) and the other $2,000 of nonrefundable credit provides no benefit. Your refund depends on refundable credits and withholding, not this line alone.

Related lines on your return

• Line 19 — Form 1040 — Child Tax Credit and Credit for Other Dependents
• Line 20 — Form 1040 — Schedule 3 nonrefundable credits
• Line 22 — Form 1040 — Tax after credits; line 18 minus line 21 (but not below zero)