Child Maintenance Calculator
Written by James Whitfield · Last reviewed 29 October 2026 · Rules from the Child Support Act 1991 and DWP guidance
Estimate weekly child maintenance under the Child Maintenance Service (CMS) rules for England, Scotland and Wales, with shared care, other children and Collect and Pay fees. Every step of the sum is shown. Northern Ireland uses the same rates through its own service.
Your details
Figures are for the paying parent. Nothing you enter is stored.
How this was worked out
- Gross weekly income £600.00
- Basic rate: 12% of £600.00 = £72.00
Monthly is the weekly figure × 52 ÷ 12, for planning; the CMS sets its own payment schedule. Collect and Pay adds 20% for the paying parent and takes 4% from the receiving parent; Direct Pay has no fees.
Agreeing it yourselves? The Child Maintenance Pack has this worksheet on paper, an arrangement template, a shared-care diary and a payment record (£4.99, one-off).
How child maintenance is worked out
The CMS takes the paying parent's gross weekly income (annual income ÷ 365 × 7), takes off personal pension contributions, and charges 12% for one child, 16% for two or 19% for three or more on income from £200 to £800 a week. Above £800 the extra is charged at 9%, 12% or 15%, up to £3,000 a week. Between £100 and £200 a reduced rate applies, and £7 to £100 a week, or a qualifying benefit, gives a flat £7.
If the paying parent supports other children at home, their counted income is cut by 11%, 14% or 16% first. Overnight stays then reduce the amount: one-seventh off at 52 nights a year, two-sevenths at 104, three-sevenths at 156, and half at 175 or more, plus £7 a week off for each child in that top band. It cannot go below £7 a week.
| Paying parent's income | 1 child | 2 children | 3 children |
|---|---|---|---|
| £150 a week | £15.50 | £19.50 | £22.50 |
| £300 a week | £36 | £48 | £57 |
| £600 a week | £72 | £96 | £114 |
| £1,000 a week | £114 | £152 | £182 |
Weekly amounts before shared care, no other children.
What this calculator cannot do
- Payments to more than one receiving parent, variations for extra income or expenses, and nil-rate cases such as a parent in prison or under 16. Use the official GOV.UK calculator.
- Decide who provides day-to-day care. Equal overnight stays alone do not mean nothing is due; the CMS decides.
- Apply the fee changes proposed in June 2025. They need new legislation and have not started.
Sorting out your money after separating?
The Family Money Pack brings together Child Benefit, Universal Credit, childcare support and a practical checklist for parents. £4.99, one-off.
See the Family Money PackRelated
Child maintenance hub · Shared-care nights calculator · CMS rates explained · Child maintenance and Universal Credit · Benefits after separation
Sources: Child Support Act 1991, Schedule 1; Child Support Maintenance Calculation Regulations 2012; DWP step-by-step guide (updated 1 April 2026); GOV.UK Collect and Pay fees. Checked 29 October 2026. An independent estimate, not a CMS decision.