Delaware is one of a small number of states using the Melson Formula rather than a straight income-shares or percentage model, implemented through Family Court Civil Rules 500-510 and worksheet Form 509 (revised February 2026, effective February 1, 2026). Under Melson, each parent first keeps a $1,600 self-support allowance, then the children’s primary needs are covered on a pro-rata basis, and only after that does a standard-of-living adjustment (12%, 17%, 21%, and up, scaling with the number of children) get layered on top. Unlike most states, Delaware’s formula does not deduct income tax from net income before running these steps.
Key facts
| Model | Melson Formula — Del. Fam. Ct. Civ. R. 500-510, Form 509 (Rev. 2/26, eff. 2026-02-01) |
|---|---|
| Self-support allowance | $1,600/month per parent |
| Standard-of-living adjustment | 12%/17%/21%… scaling by number of children |
| Tax treatment | Delaware net income does not deduct income tax |
Official source: https://courts.delaware.gov/family/
Custody arrangements covered
- Melson’s three-step structure (self-support allowance → pro-rata primary need → standard-of-living adjustment) applies uniformly, then adjusts for the paying parent’s share
Frequently asked questions
What formula does Delaware use for child support?
The Melson Formula, one of only a few states to use it, run through worksheet Form 509 (Revision 2/26, effective February 1, 2026).
How much does each Delaware parent keep before support is calculated?
A $1,600/month self-support allowance is protected for each parent before the children’s primary needs are covered.
What is the standard-of-living adjustment in Delaware?
An additional percentage — 12%, 17%, 21%, and rising with more children — added on top of the children’s basic pro-rata needs, reflecting that they should share in a parent’s higher income.
Does Delaware deduct income tax before calculating support?
No — unlike most states’ guidelines, Delaware’s net income figure under the Melson Formula does not subtract income tax.
Update history
- — Delaware went live using the Melson Formula (Form 509, effective 2026-02-01): each parent keeps a $1,600 self-support allowance, the children's basic needs are covered pro-rata, then a standard-of-living adjustment is added. Delaware's formula does not deduct income tax from net income.