How to modify child support or alimony in Oklahoma

Sources last checked: 4 November 2026. Information only, not legal advice. The Cusp is not a law firm.

Oklahoma divorce kit How child support is calculated Alimony in Oklahoma Legal aid in Oklahoma After your divorce

The short version

In Oklahoma, child support can be changed under 43 O.S. section 118I and alimony under section 134. For child support the question is whether there has been a “material change in circumstances”. For alimony paid as support, the decree can be modified on proof of changed circumstances that are “substantial and continuing”. Timing matters for both. A child support change takes effect on “first day of the month following the date the motion to modify was filed” unless the parties agree otherwise or the court finds the change happened later. Alimony changes are prospective only. We did not find a single court-published form for a contested motion to modify; the Oklahoma court network’s child support page sends readers to the Department of Human Services for child support forms.

Tests for child support

Material change in circumstances, section 118I(A): the statute says this “includes, but is not limited to” a change in the child’s needs, a change in either parent’s income, a parent’s incarceration for more than 180 consecutive days, changes in actual annualized child care expenses, changes in the cost of medical or dental insurance, or a child reaching the age of majority or otherwise ceasing to be entitled to support.
Equity: the court “shall apply the principles of equity” and looks at the best interests of the children.
A new guideline schedule is not enough: a change to the Child Support Guideline Schedule “shall not alone be a material change in circumstances”.
No retroactive change: a support order “shall not be modified retroactively”. The effective date is the first of the month after the motion was filed, unless the parties agree to another date or the court makes a specific finding that the change occurred later.
Last child: a child reaching majority is a material change but “shall not automatically serve to modify the order”. When the last child ceases to be entitled to support, the obligation ends automatically as to future support only.
Incarceration: an obligor held 180 or more consecutive days is presumed unable to pay, and the obligation is abated without court action from the first day of the month after entry into the facility. It reverts to the earlier amount the first day of the month after 90 calendar days following release. The presumption does not apply, for example, where the crime is for failure to pay child support or the offense victimized the other parent or child.
Deviation from guidelines, section 118H: the court may depart from the guideline amount if it is in the child’s best interests and the guideline amount is “unjust or inappropriate under the circumstances” or the parties agree and are represented by counsel, and it must make “specific findings of fact”.

Tests for alimony

General rule, section 134(D): alimony as support may be modified on “proof of changed circumstances relating to the need for support or ability to support” that are “substantial and continuing” so that the decree terms are unreasonable to either party. The court may change the terms of payment and the total amount, but “only have prospective application”.
Effective date: section 134(B) also says “Any modification of alimony payments shall be effective upon the date of the filing” of the requested modification. Read together with the prospective-only rule, this suggests relief starts no earlier than filing, so file promptly.
Cohabitation, section 134(C): voluntary cohabitation of the former spouse with a member of the opposite sex is a ground to modify. The court may reduce or end future support on proof of a substantial change in circumstances relating to need or ability to support. The statute defines cohabitation as dwelling together continuously and habitually of a man and a woman in a private conjugal relationship not solemnized as a marriage. We read no case applying it.
Death or remarriage, section 134(B): the decree must provide that support ends on the recipient’s death or remarriage. The recipient who wants support to continue after remarriage must start an action within 90 days of the remarriage.
Property payments cannot be changed: payments designated as a division of property are “irrevocable and not subject to subsequent modification” (section 134(A)). Only the part the decree designates as support can be modified.
Older decrees: section 134(J) applies the cohabitation and general modification rules to alimony orders “regardless of the date” they were entered.

Forms

Agreed child support changes: section 118I(D)(5) says that if parents agree to modify, the agreement “shall be in writing using standard modification forms” plus the child support computation form from section 120. The court reviews them to confirm they follow the guidelines or approves a deviation under section 118H.
Where the child support forms are: the Oklahoma State Courts Network child support forms page says the forms are prepared by the Department of Human Services under section 120 and can be found on that agency’s website. We did not read that website.
District court forms: the district court forms page lists an initial bail order form and protective order forms. We found no modification form there.
Alimony: we found no official form for a motion to modify alimony. Ask the clerk of the court that entered your decree.
A copy of the order you want changed. Our sources do not list it as required, but any motion will need to identify it.

Before you file

Court staff cannot give legal advice. See legal aid in Oklahoma for free or low-cost help, or the Oklahoma divorce kit for the wider process.
Timing matters: child support and alimony changes cannot reach back before the motion is filed, so file as soon as your circumstances change.
Informal review: if your order has no review clause, either parent may ask the other for the information needed, and it must be provided “within forty-five (45) days of the request”. Section 118I(D) says this exchange may occur once a year or less often, and may include income, insurance cost and child care cost information.
This page does not state a filing fee. No official source we read states an amount.
See how child support is calculated in Oklahoma and alimony in Oklahoma. For other changes after a divorce, see After your divorce.

What we could not confirm

A court form for a contested motion to modify. We found none on the court pages we read.
The Department of Human Services forms and its review process. We did not read them.
Filing fees and any deadline or method for serving the other party.
How judges apply the tests. We read no court opinions.
Alimony effective date. Section 134 says both that a modification is effective on the filing date and that it applies only prospectively. We do not know how courts reconcile them.
Guideline amounts and the computation. We did not read sections 118A to 118G, 119 or 120.
Court rules. We read no local or Supreme Court rules on motions to modify.
Most of section 118H and subsections of section 134 on military retirement pay and veterans benefits, which we did not summarize.

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