Child support modification calculator

Enter today's circumstances to get the new guideline amount, then compare it with your current order and your state's threshold for a change.

State

Children live mostly with

Parent BParent AAbout equally

Parent A (you) gross income

Parent B (the other parent) gross income

Include wages, self-employment, bonuses, and other income the guidelines count.

Guideline child support

Choose your state and enter both incomes to see the guideline amount.

Compare with your current order

Current monthly order

Fill in the calculator above with the new circumstances to see the new guideline amount.

How it works

A child support order stays the same until a court or child support agency changes it, even when incomes, parenting time or the children's needs change. To see whether a change might be worth asking for, compare the current order with the guideline amount for the circumstances as they are now.

The calculator at the top works exactly like the main calculator: choose your state and enter both parents' current incomes, the number of children and anything else that applies under More options. The comparison below it then shows the difference from your current order, in dollars and as a percentage.

States handle the question differently. Some presume a change is warranted once the guideline amount differs from the order by a set percentage, a set dollar amount, or both; some add conditions such as the order being a few years old; others look for a substantial change in circumstances without a fixed number. The comparison applies your state's rule where it has one and links to the official way to ask for a review.

A difference that meets the threshold doesn't change the order by itself, and a court can still decline a change or deviate from the guidelines. A difference below the threshold doesn't rule out a change either if there is another substantial change in circumstances.

Worked example

In Texas, with 2 children living mostly with Parent B, who earns $40,000, the guideline amount is $882 a month when Parent A earns $50,000 a year. If Parent A's income rises to $70,000, the guideline amount becomes $1,210 a month, a change of $327. That meets the Texas threshold of 20% or $100 a month for an order at least three years old.

Modification thresholds by state

When the states this site covers presume a change to a child support order
State	Threshold	Rule
Alabama	more than 10%	In Alabama, a change is presumed appropriate when the guideline amount differs from the current order by more than 10%, and there must be a material change in circumstances that is substantial and continuing. A change in a child's health care needs can be enough on its own, but new guidelines alone are not. A modification applies only to payments due after the request is filed. The state child support agency (DHR) reviews an order once every 36 months unless there is a significant change.
Alaska	more than 15%	Alaska presumes a material change of circumstances when child support calculated under Civil Rule 90.3 is more than 15% higher or lower than the current order; health insurance payments count toward the comparison. The Child Support Enforcement Division uses the same 15% test for administrative orders. A change can't apply before the date the motion or the agency's notice of petition for modification was served.
Arizona	15%	Under the Arizona guidelines, a difference of at least 15% from the current order is evidence of a substantial and continuing change; a party in a state agency case may also ask for a review every three years.
Arkansas	Substantial change (no fixed percentage)	In Arkansas, a change in the paying parent's gross income of 20% or more a month is the standard for asking the court to modify support, and either parent can ask the state child support office to review an order every three years. A difference between the current order and the amount the Family Support Chart gives is a material change of circumstances, unless it doesn't meet that standard, results from a deviation whose reasons haven't changed, or is due only to a revised chart. A new support obligation for other children isn't enough on its own.
California	20% or $50 a month	California courts can modify support at any time circumstances change. The child support agency generally modifies an order when it would change by 20% or $50 a month, whichever is less.
Colorado	10%	In Colorado, applying the guidelines to the current circumstances must change the monthly amount by at least 10%; a smaller change is not a substantial and continuing change. A modification applies only from the date the motion is filed. In agency cases, a parent may also ask for a review three years after the last one.
Connecticut	15%	In Connecticut, a support order can be modified when either parent's circumstances change substantially, or when the order differs from the guideline amount by 15% or more. A difference of less than 15% is presumed not to be substantial. A change usually can't reach back before the other parent was served with the motion.
Delaware	more than 10%	In Delaware, a petition filed within two and a half years of the last support order must show a substantial change in circumstances the petitioner didn't cause, and the order changes only if the new calculation differs by more than 10%. After two and a half years neither requirement applies. An update of the formula's figures alone is not a reason to modify.
District of Columbia	15%	In the District of Columbia there is a presumption of a substantial and material change when the guideline applied to current circumstances gives an amount 15% or more different from the existing order; a change to the guideline itself counts too. Every 3 years parents can ask the Child Support Services Division for a review. A parent can also seek a change at any time by showing a substantial and material change in the child's needs or the paying parent's ability to pay. Changes can't reach back before the other parent was notified of the motion.
Florida	15% and $50 a month	Florida requires the new guideline amount to differ from the order by at least 15% or $50 a month, whichever is greater.
Georgia	Substantial change (no fixed percentage)	Georgia modifies support on a substantial change in either parent's income and financial status or the child's needs; there is no fixed percentage.
Hawaii	10%	In Hawaii a material change in circumstances is presumed when support under the current guidelines is 10% more or less than the existing order. A parent can ask the Family Court or CSEA to review an order that is three or more years old without showing any change; an order less than three years old needs a substantial and material change, such as a change in income, custody or health care costs.
Idaho	Substantial change (no fixed percentage)	Idaho courts modify child support only on a showing of a substantial and material change of circumstances, and only for installments due after the motion is filed. A change in the guideline amount may itself be such a change; there is no set percentage. Idaho Child Support Services reviews an order at either parent's request after three years, or sooner if a substantial change has lasted at least six months.
Illinois	20% and $10 a month	Illinois allows modification on a substantial change. In child support agency cases at least 36 months old, a difference of at least 20% (and no less than $10 a month) qualifies without showing a change.
Indiana	more than 20%	Indiana can modify support when circumstances change so substantially and continuously that the order becomes unreasonable. It can also modify when the guideline amount differs from the order by more than 20% and the order is at least 12 months old. A change applies back no earlier than the date the petition was filed.
Iowa	10%	In Iowa, a substantial change of circumstances exists when the current order varies by 10% or more from the amount due under the current guidelines, or when a parent has health coverage available and the order has no medical support provisions (Iowa Code § 598.21C(2)). Courts also weigh other changes in circumstances. Child Support Services' administrative modification process requires a change of 50% or more in a parent's income (Iowa Code § 252H.18A).
Kansas	10%	Under the Kansas guidelines, a change in the parents' finances or in the guidelines that would raise or lower the basic child support obligation (worksheet Line I.2) by 10% is a material change of circumstances that warrants review. So is a child moving into a higher age group. An increase in the income of the parent with primary residency, or new second-job or overtime income of the other parent, isn't enough on its own.
Kentucky	15%	In Kentucky, applying the guidelines to current circumstances and getting an amount at least 15% higher or lower than the current monthly order is presumed to be a material change that supports modification; a smaller change is presumed not to be. A modification applies only to payments that come due after the motion to modify is filed. A 15% change in the number of parenting time days can also support a request.
Louisiana	25%	In Louisiana a support order can be changed when a party shows a material change in circumstances that is substantial and continuing. Where DCFS provides child support services, a change of at least 25% under the guidelines is presumed to be a material change, and DCFS may review an order every three years. A change in the guidelines alone isn't a material change, and a modification generally reaches back to the date the request was filed.
Maine	more than 15%	In Maine, an order that differs by more than 15% from the guideline amount is a substantial change of circumstances. If the order is less than 3 years old, it is modified to the guidelines; if it is 3 years old or more, it is reviewed without proof of a change and modified whenever the guideline amount differs. Changes apply back only to the date the other party was served with the motion.
Maryland	Substantial change (no fixed percentage)	In Maryland, a court can change a child support order after a motion to modify is filed and a material change of circumstance is shown. The law sets no percentage. The Maryland Judiciary's People's Law Library says a change in a parent's income of 25% or more is usually enough. A change can't reach back before the motion was filed. The child support agency reviews orders on request every three years.
Massachusetts	Substantial change (no fixed percentage)	An order may be modified when it is inconsistent with the amount the guidelines would give, when health coverage changes, or on any other material and substantial change in circumstances. There is no fixed percentage or dollar threshold. The Department of Revenue reviews the orders it enforces every three years, or sooner on request.
Michigan	10% and $50 a month	Michigan's Friend of the Court petitions for a change when the new amount differs from the order by 10% or $50 a month, whichever is greater. Reviews are available every 36 months.
Minnesota	20% and $75 a month	In Minnesota, a change is presumed substantial when applying the guidelines to the parents' current circumstances gives an amount at least 20% and at least $75 a month higher or lower than the current order (only the 20% test applies when the current order is under $75). Other grounds include a parent's gross income dropping by at least 20% through no fault or choice of their own. A change usually reaches back only to the date the other parent was served with the motion.
Mississippi	25%	Either parent can ask MDHS to review an order every three years without showing a change in circumstances; an earlier review needs a substantial change, which MDHS defines as including a 25% change in either parent's adjusted gross income. MDHS seeks a modification when the guideline amount is 25% a month more or less than the current order. A change applies only from the date the other parent was notified of the petition.
Missouri	20%	In Missouri, a change of 20% or more between the current order and the guideline amount is a prima facie showing of a substantial and continuing change, if the current order was based on the guideline amount. The Family Support Division reviews orders that are at least 36 months old, or sooner after a substantial change.
Montana	15%	In Montana, CSSD reviews an order 36 months after it was entered or last reviewed, or sooner after a substantial change in circumstances, for example a change of at least 30% in a parent's income or a child moving to the other parent's home. If the new guideline amount differs from the current order by less than 15%, the change may be treated as negligible and the order left as it is. A court modifies support on a substantial and continuing change, on written consent, or on a CSSD application, and not within 12 months of the last order.
Nebraska	10% and $25 a month	In Nebraska, if applying the guidelines would change the current child support, child care or health care obligation by 10% or more, and by at least $25, up or down, because of financial circumstances that have lasted 3 months and are expected to last another 6 months, that is presumed to be a material change in circumstances. An obligor can't get an existing order lowered just because they have a new child, and an obligor's support can't go up only because the other parent's income rose.
Nevada	Substantial change (no fixed percentage)	In Nevada, a child support order can be reviewed at any time when circumstances change, and a change of 20% or more in the gross monthly income of a parent subject to the order is deemed a change in circumstances that requires a review. A parent or the child support agency can also ask the court to review the order at least every three years. A new version of the guidelines is not by itself a change in circumstances, and a change can only reach payments that were not yet due when a party gave notice of a motion to modify.
New Hampshire	Substantial change (no fixed percentage)	In New Hampshire either parent may ask the court (or DHHS, if it issued the order) to modify support three years after the last order without showing any change in circumstances, and at any time if there has been a substantial change in circumstances. The law sets no percentage or dollar threshold. A change can't take effect before the other party was given notice of the petition.
New Jersey	Substantial change (no fixed percentage)	Either parent can ask the court to change an order at any time. The court must first find that circumstances have changed since the order was entered; new guidelines alone are not a reason to modify. There is no fixed percentage or dollar threshold. Orders enforced by the child support program get a review notice every three years, and orders set or changed after September 1, 1998 are eligible for a cost-of-living adjustment every two years.
New Mexico	more than 20%	In New Mexico, a court may modify child support on a showing of a material and substantial change in circumstances, including the children's health care needs. A change is presumed when applying the guidelines would move the support up or down by more than 20% and the petition is filed more than one year after the existing order was filed. The state child support agency reviews orders in its caseload three years after the last order and, for families receiving public assistance, pursues a change of at least 20%.
New York	Substantial change (no fixed percentage)	New York modifies support on a substantial change, after three years, or when either parent's gross income changes by 15% or more (unless the parents opted out in writing).
North Carolina	15%	North Carolina presumes a substantial change when an order at least three years old differs from the guideline amount by 15% or more.
North Dakota	more than 15%	When Child Support reviews an order and the current amount is less than 85% or more than 115% of the guideline amount, it must ask the court to amend the order. A court amends an order entered at least one year earlier to the guideline amount whether or not circumstances have materially changed; within one year a material change must be shown. Either parent can ask Child Support for a review, generally every 18 months for cases with full services, and orders are reviewed at least every 36 months on request.
Ohio	more than 10%	Ohio treats a recalculated amount more than 10% above or below the current order as a change of circumstances that requires modification.
Oklahoma	20% and $30 a month	Oklahoma law lets a court modify a child support order when there is a material change in circumstances, without a set percentage; a change in the guideline schedule alone is not enough. In cases handled by Oklahoma Human Services Child Support Services, a material change means the support would go up or down by 20% and by at least $30 a month. A modification usually takes effect the first day of the month after the motion is filed and can't reach back before that.
Oregon	more than 15% or $50 a month	In Oregon, the Child Support Program reviews an order for a change in circumstances (parenting time, finances or the children's needs) only if the order is not in substantial compliance with the guidelines: the new guideline amount must differ from the current order by more than $50 or 15% of the new amount, whichever is less. An order that took effect more than 35 months ago can be reviewed regardless. Courts can modify on a substantial change in economic circumstances.
Pennsylvania	Substantial change (no fixed percentage)	Pennsylvania modifies support on a material and substantial change in circumstances; there is no fixed percentage. Orders can be reviewed at least every three years on request.
Rhode Island	10%	In Rhode Island an order can be modified when circumstances have changed substantially. The guidelines presume there is no substantial change if the new guideline amount would be less than 10% higher or lower than the current order. Every three years from the last order, either parent or the State can ask for a review and adjustment to the guidelines without proving a change. Changes are retroactive only to the date the other party got notice of the motion.
South Carolina	Substantial change (no fixed percentage)	South Carolina sets no percentage threshold for changing an order. The family court can modify child support when circumstances have changed, and a new guideline amount alone isn't a change in circumstances except in cases handled by the state child support program. In those cases the Department of Social Services reviews an order every three years on request and adjusts it if it differs from the guideline amount. Only payments that come due after a modification can be changed.
South Dakota	Substantial change (no fixed percentage)	South Dakota sets no percentage or dollar threshold. A support order can be modified on a substantial change in circumstances if the petition is filed within three years of the order, and without showing any change if it is filed after three years. Orders in effect before July 1, 2026 can be modified under the current guidelines without showing a change in circumstances. Only the circuit court can modify an order; the Division of Child Support has a petition form.
Tennessee	15%	In Tennessee, an order can generally be modified when there is a significant variance: at least a 15% difference between the current support order (not counting any deviation) and the new guideline amount. A change in a child's health care coverage needs is a separate reason. A modification usually can't reach back before the request was filed and the other parent was notified.
Texas	20% or $100 a month	Texas presumes a change is warranted when at least three years have passed and the guideline amount differs from the order by 20% or $100 a month; any material and substantial change also qualifies.
Utah	15%	In Utah, after a substantial change in circumstances (for example, a change of 30% or more in a parent's income), a court adjusts the order when the guidelines give an amount at least 15% higher or lower than the current order and the difference is not temporary. If the order hasn't been issued or modified in the past three years, a difference of 10% or more is enough, with no need to show a substantial change. A change in the child support tables alone is not a substantial change.
Vermont	more than 10%	A court can change an order after a real, substantial and unanticipated change of circumstances. An order that differs by more than 10% from the guideline amount counts as such a change, as do workers' compensation, disability or means-tested benefits, unemployment compensation, and incarceration for more than 90 days. If the order has not been modified for at least three years, the court may waive the change-of-circumstances showing. The Office of Child Support reviews orders every three years for families with full services.
Virginia	10% and $25 a month	Virginia courts can change support when circumstances change, but only back to the date the other parent was notified of the request. For child support agency reviews, a guideline amount that differs from the order by at least 10% and at least $25 a month is a material change; either parent can ask for a review every three years.
Washington	15%	A parent can ask to modify a Washington order at any time on a substantial change of circumstances. After 24 months an order can be adjusted for changes in income or in the economic table without that showing. The Division of Child Support may seek a modification when the order is at least 15% above or below the standard calculation on current incomes.
West Virginia	more than 15%	In West Virginia, a child support order can be modified when circumstances change substantially. If applying the guidelines would give a new amount more than 15% different from the current order, the change is considered substantial. A parent whose income changes can use the expedited modification process, and either parent can ask the Bureau for Child Support Enforcement to review an order three years after it took effect, or sooner with a substantial change. Support stays due until a motion to modify is filed.
Wisconsin	$50 a month	A Wisconsin court can change support only after a substantial change in circumstances, which is presumed once 33 months have passed since the last order. The child support agency reviews an order on request every three years and may seek a change when the support amount would change by $50 or more a month.
Wyoming	20%	In Wyoming, a party (or the Department of Family Services in cases it enforces) may petition for review of an order entered or adjusted more than six months earlier. If applying the guidelines would change the support amount by 20% or more a month, the court treats that as a change of circumstances sufficient to modify the order. A party may also seek a modification at any time based on a substantial change of circumstances, and every three years an order can be reviewed and adjusted on request without showing a change in circumstances. Support can't be changed retroactively, except by agreement or back to the date the other party was served with the petition.

Frequently asked questions

When can child support be modified?

Every state lets a parent ask for a change when circumstances change substantially, such as a large change in income or in the children’s needs. Many states also set a presumptive threshold: if the new guideline amount differs from the current order by a set percentage or dollar amount, a change is presumed.

Does a new guideline amount change my order automatically?

No. The order stays in force until a court or the child support agency changes it. In most states a change applies only from the date the request was filed or served, so asking promptly matters.

How do I ask for a modification?

You can ask the court that made the order or, in many states, the state child support agency, which can review the order for free. The result on this page links to your state’s process.