8 — Excess AGI Over Threshold Updated for tax year 2025

What this line means

The amount by which your modified AGI exceeds the threshold from line 7. You subtract line 7 from line 4 and round up to the next $1,000. If your modified AGI is at or below the threshold, this line is zero and you get the full credit. This excess amount feeds into the phaseout calculation on line 9.

Does this apply to you?

• You are calculating whether your child tax credit is reduced by the income phaseout
• Your modified AGI on line 4 exceeds $200,000 (or $400,000 if married filing jointly)

Easy to overlook

The excess is rounded up to the nearest $1,000 You do not use the exact dollar amount of the excess. If your modified AGI exceeds the threshold by $5,200, you round up to $6,000. This rounding rule means even $1 over a $1,000 increment triggers the next level of phaseout reduction. Filers sometimes use the exact difference and understate the reduction. ¹ [SOURCE: IRS Schedule 8812 instructions — line 8 computation]

A zero on this line means no phaseout If your modified AGI is below the threshold, line 8 is zero, line 9 is zero, and your credit on line 10 equals the full amount from line 6. Most families have zero on this line because the $200,000/$400,000 thresholds are high enough to cover the majority of filers. ² [SOURCE: IRC Section 24(b) — phaseout calculation]

Watch out for this

Forgetting to round up. The instructions require rounding the excess to the next highest multiple of $1,000. Using the exact dollar difference instead of the rounded amount produces a slightly lower phaseout reduction and overstates the credit. Tax software handles the rounding automatically, but paper filers miss this step.

Related lines on your return

• Line 4 — Schedule 8812 — Modified AGI; the starting point
• Line 7 — Schedule 8812 — AGI threshold amount; subtracted from line 4
• Line 9 — Schedule 8812 — Phaseout reduction; line 8 multiplied by 5%