Quick answer: California child support can be modified at any time as the court determines to be necessary, but only from the date you file the notice of motion or order to show cause (or a later date). The statutes we read set no percentage threshold, and support that accrued before the filing cannot be changed.
This California child support modification calculator compares your order with the amount the guideline gives today (you can get it from the California child support calculator) and shows the monthly difference and what that difference could be worth if the court makes the change retroactive to the filing date under Fam. Code 3653. Unemployment has its own retroactivity rule, and if the existing amount was a stipulation below the guideline, no change of circumstances needs to be shown to modify to the guideline level or above.
California child support modification at a glance
| Rule | What California says |
|---|---|
| Standard | A support order may be modified or terminated at any time as the court determines to be necessary (Fam. Code 3651(a)) |
| Accrued support | May not be modified as to an amount that accrued before the filing of the notice of motion or order to show cause (3651(c)(1)) |
| Retroactivity | To the filing date or any later date (3653(a)) |
| Unemployment | Retroactive to the later of service of the motion or the date of unemployment, unless good cause (3653(b)) |
| Stipulation below guideline | No change of circumstances needed to modify to the guideline level or above (4065(d)) |
| Percentage threshold | We found none in the statutes we read |
How does child support modification work in California?
- Know the standard and the dates. See what counts as a change in circumstances in California.
- File the right forms. See how to modify child support in California.
- Income problems. See reducing child support after job loss or incarceration in California and, for what stays owed from before the filing, the California child support arrears calculator.
What does this modification calculator check?
The calculator shows the gap between your order and the guideline amount, the effect of retroactivity to the filing date, the unemployment rule and the stipulated-order rule. It cannot say whether the court will modify, because California’s statute leaves that to the court. The months before you file are the ones you cannot recover.
Frequently asked questions
How much does child support have to change to be modified in California?
The statutes we read set no percentage. A support order may be modified or terminated at any time as the court determines to be necessary, and the court decides whether the change justifies it.
From what date does a California child support change take effect?
An order modifying support may be made retroactive to the date of the filing of the notice of motion or order to show cause, or to any later date. A support order may not be modified as to amounts that accrued before the filing.
Is unemployment treated differently for a California modification?
Yes. If the order is entered because of the unemployment of either parent, it is made retroactive to the later of the date of service of the motion or the date of unemployment, unless the court finds good cause not to.
Do I need a change in circumstances if my support was stipulated below the guideline in California?
No. If the parties stipulated below the statewide guideline amount, no change of circumstances needs to be demonstrated to modify to the guideline level or above.
Can I get back money I overpaid after a retroactive decrease in California?
The court can order the support obligee to repay the excess, over any period and by offset or wage assignment, after considering the amount, the duration of the order, the financial impact and other relevant facts.
Official sources
- Cal. Fam. Code 3651: modification and termination of support
- Cal. Fam. Code 3653: retroactive modification
- Cal. Fam. Code 4065: stipulated child support
- Cal. Fam. Code 3664: request for an income and expense declaration
- California Judicial Council: Information Sheet for Request for Order (FL-300-INFO)
- 42 U.S.C. 666(a)(9): no retroactive modification of support already due