Child Tax Credit Calculator (2026)

How the child tax credit fits on a return

The child tax credit (CTC) directly reduces federal income tax dollar-for-dollar for each qualifying child under age 17. Unlike a deduction—which only saves tax at your marginal rate—a $2,000 credit (under the classic structure this tool models) saves $2,000 of tax if you have enough liability to absorb it. Leftover credit may flow to the additional child tax credit (ACTC), which can be refundable up to certain limits depending on earned income and other tests.

That layering matters for refund planning. A household with low income tax before credits might receive much of the benefit as a refundable payment through ACTC rather than as a reduction of tax owed. High-income households hit phaseouts that shrink or eliminate the credit even with multiple children.

This calculator is intentionally labeled as a simplified model. Tax legislation—including potential OBBBA changes—can alter credit amounts, refundability, or age limits for a given tax year. Use the output for planning conversations and W-4 tuning, then verify against IRS Form 1040 instructions and Schedule 8812 before filing.

2026 context: brackets, AGI, and phaseouts

CTC phaseouts reference modified adjusted gross income (MAGI), not taxable income after the standard deduction. For many filers MAGI equals AGI. The 2026 standard deduction—$16,100 single, $24,150 head of household, $32,200 joint—still affects how much ordinary tax you owe before credits apply, but it does not change the phaseout threshold itself.

If you are estimating total tax, run the federal income tax calculator first for ordinary liability, then layer CTC here. For refund-oriented math, connect both to the tax refund estimator once withholding is known.

Qualifying child tests (summary)

A qualifying child for CTC generally must:

• Be under 17 at the end of the tax year
• Be your son, daughter, stepchild, foster child, sibling, or descendant of those
• Not provide more than half of their own support
• Have lived with you for more than half the year (with exceptions)
• Be claimed as your dependent and have a valid SSN

Dependents who age out, non-citizens without valid SSNs, or children claimed on another return fail eligibility even if you financially support them. The IRS tie-breaker rules decide which parent claims a child after divorce when both households otherwise qualify.

Phaseout mechanics

Under the classic model, credit begins phasing out when MAGI exceeds $200,000 for single and head of household filers or $400,000 for married filing jointly. The reduction is $50 for each $1,000 (or part of $1,000) over the threshold. A joint filer at $420,000 MAGI is $20,000 over—potentially a $1,000 reduction before counting children. Multiple children multiply the pre-phaseout credit, but one phaseout formula applies to the total.

Near-threshold planning: a Roth conversion or bonus that spikes MAGI can cost more in lost CTC than the obvious marginal rate suggests. Compare scenarios in the tax year comparison tool when timing income.

Non-refundable vs refundable portions

Child tax credit (non-refundable slice)

The non-refundable CTC reduces tax owed but cannot push liability below zero by itself. If you owe $3,000 before credits and qualify for $4,000 of CTC, $3,000 offsets tax and $1,000 may move toward ACTC if earned-income tests are met.

Additional child tax credit (refundable slice)

ACTC uses earned income floors and caps—historically tied to 15% of earned income above a threshold with a per-child maximum on the refundable portion. Exact parameters change with law; this engine applies a simplified ACTC path. Low-income workers with children often depend on ACTC for a meaningful refund even when federal income tax withholding was small.

Worked example

Married filing jointly, $95,000 AGI, two qualifying children under 17, standard deduction, classic $2,000 per child before phaseout:

• Taxable income roughly $62,800 after the $32,200 standard deduction
• Ordinary tax stacks mostly in 10% and 12% bands—see federal calculator for exact cents
• Pre-phaseout CTC: $4,000; MAGI below $400,000 so no phaseout
• Credit wipes most or all income tax; any remainder flows toward ACTC if earned-income rules allow

Same family at $410,000 MAGI begins losing credit via phaseout even though children still qualify on dependency tests.

W-4, paychecks, and surprise balances

Form W-4 Step 3 converts expected dependent credits into lower withholding. Overstating children or ignoring phaseouts produces higher take-home pay during the year and a smaller refund—or a balance due—in spring. After a pay raise crosses a phaseout threshold, revisit W-4 with the W-4 withholding calculator.

Related credits and tools

• EITC calculator — separate earned income credit with its own rules; you may qualify for both EITC and ACTC when eligible
• Dependent care FSA calculator — childcare benefits, not CTC, but part of the same household budget picture
• SNAP calculator — nutrition benefits use different income tests than tax credits

Common mistakes

• Counting a child who turned 17 before year-end
• Using taxable income instead of MAGI for phaseout checks
• Assuming OBBBA-expanded amounts without reading current IRS guidance
• Double-counting the same child on two returns
• Ignoring that credit reduces tax before withholding reconciliation in the refund estimator

Credit for other dependents (ODC)

Dependents who are not qualifying children for CTC—college students 17+, elderly parents, certain relatives—may qualify for the $500 credit for other dependents (ODC) when dependency tests are met. ODC is non-refundable and follows its own phaseout pattern in recent law. Do not count the same person for both full CTC and ODC.

Interaction with the earned income tax credit

EITC and CTC/ACTC serve different policy goals but often appear on the same low- to moderate-income return. EITC depends on earned income, investment income limits, and household structure without requiring children (though childless EITC is smaller). ACTC refundable portion uses its own earned-income formula. Receiving one does not automatically disqualify the other, but combined refund math can trigger bank hold rules on large refunds—plan cash flow accordingly.

Documentation the IRS may request

Keep birth certificates, school records, medical provider letters for disability exceptions, Form 8332 releases, and proof of residency. The IRS can deny credits in audit if substantiation fails even when you entered numbers correctly in a calculator.

Year-end moves that change credit outcomes

Deferring a bonus from December to January shifts MAGI between tax years—sometimes enough to escape or trigger phaseout. Roth conversions and large capital gains realizations count toward MAGI for credit phaseouts even when no withholding was taken. Model those moves in the capital gains tax calculator before executing trades in December.

Split custody and the tie-breaker rules

When parents live apart, only one may claim a child for CTC per year. IRS tie-breaker rules look at where the child lived longer, then adjusted gross income if time is equal. Form 8332 lets a custodial parent release the exemption to the noncustodial parent in some years—but credit rules may still follow residency, not the release, depending on the tax year’s law. Document court orders and custody calendars before you enter dependents in this calculator or on Form W-4.

Grandparents and other relatives who support a child may qualify when parents are absent, but multiple support agreements and residency tests are strict. A child who splits time evenly between two homes needs a clear tie-breaker outcome before anyone claims CTC.

OBBBA and legislative updates—verify before filing

Recent budget legislation may change credit amounts, refundability, or age limits for a given tax year. This engine uses a simplified classic CTC structure for planning conversations—not automatic application of every enacted change. Before filing, read IRS Form 1040 instructions, Schedule 8812, and Publication 972 for the year you report. IRS Notice 2025-67 and related newsroom releases supersede blog summaries.

If law expands the credit temporarily, W-4 Step 3 may still reflect old assumptions until you update withholding mid-year.

ACTC and the $2,500 earned-income floor (classic model)

Under the simplified ACTC path modeled here, refundable credit often ties to earned income above a floor with a percentage calculation and per-child caps. Low-income workers with small tax liability before credits may receive much of the benefit as ACTC rather than non-refundable CTC. Cross-check Schedule 8812 line-by-line when preparing the return—this calculator rounds and simplifies.

Qualifying child disability and age exceptions

Permanent and total disability exceptions can extend dependency and credit rules in some years. Medical documentation and physician statements support audit defense. Age-17 cutoff is strict for classic CTC—plan December birthdays carefully when dependency is borderline.

Form 8812 and repayment protection

ACTC math on Schedule 8812 uses earned income and phaseouts that differ from the simplified engine here. Excess advance CTC from prior years may reduce current refunds. Verify IRS instructions for the filing year before relying on a planning estimate for major purchases.

Credit timing with newborn dependents

A child born December 31 qualifies for the full year if other tests are met. Update Form W-4 immediately after birth so withholding reflects Step 3 credits—waiting until tax season leaves months of wrong withholding.

Planning takeaway

Treat this output as a W-4 and refund-planning input, not a filed Schedule 8812. When OBBBA or other law changes credit amounts, re-read IRS instructions and re-run the tax refund estimator with updated credit dollars before changing withholding.

Sources and disclaimer

Bracket and deduction figures align with Rev. Proc. 2025-32. CTC dollar amounts and refundability follow a simplified statutory model for education—not a filed return. Verify IRS Notice 2025-67 materials and the Form 1040 instructions for the year you file. Consult a tax professional for custody splits, ITIN situations, or adoption credit interactions.