Tested tool guide
Tested browser tools
Checked August 15, 2026
What Child Tax Credit Calculator does, with a checked example
Each qualifying child under 17 is worth up to $2,200 off your federal tax bill, but that amount shrinks once your modified adjusted gross income passes $200,000 single or $400,000 married filing jointly. Enter the number of qualifying children, your filing status, and your MAGI, and the calculator multiplies children by the per-child amount, then subtracts $50 for every $1,000 (or part of one) your income sits above the threshold. A MAGI just $1 over the threshold still triggers a full $50 reduction, since any partial $1,000 rounds up to the next bracket.
Worked example
A concrete input and expected output from the current implementation.
Input
Married filing jointly, 3 qualifying children under 17, MAGI $420,000
->
Expected output
$5,600 total credit ($6,600 base reduced by a $1,000 phase-out)
3 children x $2,200 = $6,600 base. MAGI is $20,000 over the $400,000 MFJ threshold, exactly 20 increments of $1,000; each increment cuts $50, a $1,000 reduction, leaving $5,600.