What is the 3-year review rule for child support?

Several states allow modification after 3 years without showing a specific change in circumstances. Either parent can request recalculation every 3 years. New York, Colorado, and others use this rule to prevent orders from becoming outdated.

What if the other parent refuses to disclose their income for modification?

Courts have subpoena power to compel income disclosure. You can request financial discovery through the court. If a parent refuses, courts can hold them in contempt, impute income based on earning capacity, or draw negative inferences from non-disclosure.

Child Support Modification Calculator

Q: Can child support be modified retroactively?

Generally no. Child support can only be modified going forward from the date you file. Past-due arrears cannot be retroactively reduced. File immediately when circumstances change rather than making informal agreements.

Q: Does losing your job reduce child support automatically?

No. Job loss does not automatically reduce support. You must file a modification motion immediately. The existing order continues to accrue until modified by the court. Document everything and seek temporary modification as quickly as possible.

Q: Does having a new baby reduce child support for existing children?

Having a new child may be grounds for modification in many states, but it is not automatic. Courts balance existing children's needs against the new child's. The reduction is typically modest (5-10%) and courts look unfavorably on using new children to reduce existing obligations.

Compare your current order against a new calculation. See if income changes, custody changes, or a new child meet the modification threshold in your state.

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NCP Income — Old

At time of last order

NCP Income — New

Current income

Custodial Parent Income

Number of Children

Old vs New Child Support

$1,972/mo new

Previous Order Est.$1,508/mo

New Calculation$1,972/mo

Change in Support+$464/mo

NCP Income Change+30.8%

Income changed +30.8% — likely meets the 15-20% threshold for modification in most states.

Advanced Calculator

Before/after comparison chart, 15% and 20% threshold analysis, threshold status badge, and year-by-year old vs. new support comparison.

+ Open Advanced Calculator

Current Order

Current Court Order

NCP Current Income

CP Current Income

Children (current)

New Circumstances

NCP New Income

CP New Income

Children (new)

Modification Analysis

+59.4% change

Current Order$1,200/mo

New Guideline$1,913/mo

Monthly Change+$713/mo

Likely meets modification threshold (20%+ change)

Before Modification

Court order: $1,200/mo

Guideline calc: $1,620/mo

Annual: $14,400

After Modification

New guideline: $1,913/mo

Change: +$713/mo

Annual savings: $8,550

Professional Simulator

Full income re-evaluation, 5 what-if scenarios (job loss, salary cuts, promotion, new child), arrears with interest, petition cost-benefit analysis, and 20-year lifetime projection.

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Original Order

Current Court Order/mo

Original NCP Income

Original CP Income

Children

New Circumstances — NCP Income: $58,000/yr

W-2 / Salary

Self-Employment

Bonuses

CP New Income

Children

NCP Custody %

Health Insurance/mo

Childcare/mo

Full Modification Analysis

$1,554/mo new guideline

NCP Tax Analysis

Original gross: $72,000/yr | Fed tax: $7,542

New gross: $58,000/yr | Fed tax: $4,970

Net income change: $11,428/yr

Support Comparison

Old order: $1,200/mo

New guideline: $1,554/mo

Annual change: +$4,250

Change %: +29.5%

Meets 15% ThresholdYes

Meets 20% ThresholdYes

Annual Savings/(Cost)$4,250/yr

What-If Scenarios

Scenario	New CS	vs. Order	Threshold Met
Job Loss (NCP)	$0/mo	-100.0%	Yes (15%+)
25% Income Reduction	$783/mo	-34.7%	Yes (15%+)
15% Income Reduction	$887/mo	-26.0%	Yes (15%+)
Promotion (+20%)	$1,253/mo	+4.4%	No
Additional Child	$1,237/mo	+3.1%	No

When Can Child Support Be Modified?

Child support orders are not permanent — they can be modified when circumstances change substantially. Most states require either a material change in circumstances or the passage of a set period of time (usually 3 years) before allowing modification.

Common Grounds for Modification

Significant change in either parent's income (typically 15-20% or more)
Job loss or involuntary unemployment
Change in custody arrangement or overnights
A parent having a new child with another partner
Significant change in the children's needs (medical, educational)
A child reaching the age of majority or emancipation
3-year review period (in states that allow it)

The 15-20% Income Change Rule

Many states use a 15% or 20% income change as a shorthand for "material change in circumstances." If your income has changed by this amount or more since the last order, you likely have grounds for modification. States like New York use exactly 15%; others use 20%.

Income Change % = (New Income − Old Income) ÷ Old Income × 100
Support Change % = (New Calculated Support − Current Order) ÷ Current Order × 100

Modification likely if: |Income Change| ≥ 15–20%
OR: |Support Change| ≥ $100 and ≥ 20% (Texas rule)
OR: 3 years have passed since last order (some states)

Example — Income Change

NCP income increased from $6,500 to $8,500/mo. Custodial parent earns $4,500. Two children.

Old NCP Income$6,500/mo

New NCP Income$8,500/mo

Income Change+30.8%

Old Support Estimate$1,012/mo

New Support Estimate$1,192/mo

Increase+$180/mo

30.8% income change well exceeds the 15-20% threshold — modification is warranted.

Frequently Asked Questions

Can child support be modified retroactively? ▼

Generally no. In most states, child support can only be modified going forward from the date you file the modification request. You cannot retroactively reduce past-due support (arrears). This is why it is critical to file immediately when circumstances change rather than making informal agreements with the other parent. Arrears that accumulated before filing remain owed in full.

Does losing your job reduce child support automatically? ▼

No. Job loss does not automatically reduce child support. You must file a modification motion immediately. Courts will evaluate whether the job loss was voluntary or involuntary. While your motion is pending, the existing order remains in full effect and arrears continue to accrue. If you cannot pay, document everything and seek temporary modification as quickly as possible.

Does having a new baby reduce child support for existing children? ▼

Having a new child with a new partner may be grounds for modification in many states, but it is not automatic. Courts balance the needs of the existing children against the new child's needs. Some states give priority to existing orders. The reduction, if granted, is typically modest — around 5-10%. Courts look unfavorably on parents who appear to be having new children to reduce existing support obligations.

What is the 3-year review rule? ▼

Several states — including New York, Colorado, and others — allow modification after 3 years have passed since the last order, even without showing a specific change in circumstances. Under this rule, either parent can request a recalculation every 3 years. The new order is set at the current guideline amount regardless of whether there was a dramatic change. This prevents orders from becoming outdated over time.

What if the other parent refuses to disclose their income? ▼

Courts have subpoena power to compel disclosure of income. You can request financial discovery — tax returns, bank statements, W-2s, pay stubs — through the court process. If a parent refuses to cooperate, courts can hold them in contempt, impute income based on employment history and earning capacity, or draw negative inferences from the refusal to disclose. Child support agencies can also assist with income verification.