Quick answer: In Delaware, a petition to modify child support filed within 2½ years of the last support determination must allege a substantial change in circumstances and the order changes only if the formula result differs by more than 10%. After 2½ years neither test applies. A new order starts no earlier than 3 days after the petition and summons are mailed.
This Delaware child support modification calculator applies the rules in the Family Court’s instructions for the Delaware Child Support Formula (the Family Court child support FAQ). Enter your current order and the amount the formula gives today (you can get it from the Delaware child support calculator), say whether it has been 2½ years, and it shows whether the numbers clear the line and what the difference is worth after the petition is mailed. Loss of a license or jail for not paying support is not a ground by itself.
Delaware child support modification at a glance
| Rule | What Delaware says |
|---|---|
| Within 2½ years | Allege with particularity a substantial change not caused by the petitioner’s voluntary or wrongful conduct, and the order changes only if the formula shows a change of more than 10% (Family Court instructions) |
| After 2½ years | No particularity or 10% requirement |
| Start date | No earlier than 3 days after the petition and summons are mailed (13 Del. C. 513(d)(2)) |
| Formula changes | A change caused solely by a revision of the formula is not a ground |
| Not grounds | Loss of a license and jail for nonpayment of child support (Form 342) |
| Annual exchange | The parties exchange financial report forms every 12 months and must tell each other in writing of any material change (513(c)(1)) |
How does child support modification work in Delaware?
- Know the 2½-year and 10% rules. See what counts as a substantial change in Delaware.
- File Form 342 on time. See how to modify child support in Delaware.
- Income problems. See lowering child support after job loss or incarceration in Delaware and, for what stays owed from before the petition, the Delaware child support arrears calculator.
What does this modification calculator check?
The calculator applies the 10% line only when you say less than 2½ years have passed, shows the monthly and accrued difference and notes the start date rule. It cannot decide whether your change is substantial; that is for the Commissioner after mediation. The months before the petition is mailed are the ones you cannot recover.
Frequently asked questions
How much does child support have to change to be modified in Delaware?
If support was last determined less than 2½ years ago, the formula must show a change of more than 10% and you must allege a substantial change in circumstances. After 2½ years neither requirement applies.
From what date can Delaware child support change?
No earlier than 3 days after the petition and summons are mailed to the other parent at the address on file or served personally or by signed certified mail.
Is incarceration or losing a license a ground to modify Delaware child support?
Loss of a license and jail for nonpayment are not grounds. Incarceration is not a ground to modify support last calculated within 2½ years.
Can the Delaware order reverse who pays?
Yes. A modified order can increase, decrease or reverse the payer and payee regardless of which parent filed the petition.
Does a new Delaware formula change my order automatically?
No. A change caused solely by a revision of the child support formula is not a ground for modification.
Official sources
- Delaware Family Court: Frequently Asked Questions About Child Support and Form 509i instructions
- Delaware Family Court: Form 342, Petition for Child Support Modification
- Delaware Division of Child Support Services: modification of existing orders
- 13 Del. C. 513: judgment; order of support; modification
- 42 U.S.C. 666(a)(9): no retroactive modification of support already due