UK Child Maintenance Calculator
Estimate CMS child maintenance using the 2012 Regulations formula — all five rate bands (Nil / Flat £7 / Reduced / Basic 12-16-19% / Basic Plus 9-12-15%), shared-care reductions, and court top-up above £3,000/wk.
Income band chart across all rate bands, shared care reduction visualisation, and multiple children impact table.
Full CMS calculation with income from all sources, voluntary vs court-managed comparison, special expenses, and enforcement options detail.
How UK Child Maintenance Works in 2026
The UK Child Maintenance Service (CMS) calculates maintenance using the Child Support Maintenance Calculation Regulations 2012. The calculator mirrors the official gov.uk CMS tool. Five rate bands apply based on the paying parent's gross weekly income, with adjustments for shared care and other children in the household.
The February 2024 reform abolished the £20 CMS application fee and strengthened enforcement powers. No further rate changes in 2025–2026; consultation-based reforms are not expected to land before 2027–2028.
CMS Rate Bands (2026)
(also applies to students, under 16s, certain benefit recipients, prisoners)
Flat rate: £7-£100/wk gross OR certain benefits → £7/wk fixed
Reduced rate: £100.01-£199.99/wk gross
£7 + (gross − £100) × 17% (1 child) / 25% (2) / 31% (3+)
Basic rate: £200-£800/wk gross
Gross × 12% (1 child) / 16% (2) / 19% (3+)
Basic Plus rate: £800.01-£3,000/wk gross
£800 × basic rate + (gross − £800) × 9% (1) / 12% (2) / 15% (3+)
Above £3,000/wk gross (~£156,000/yr):
CMS cannot assess — court top-up order required under §8 Child Support Act 1991
Shared Care Reductions
Where the paying parent has the children overnight, the amount is reduced. The statutory bands are based on annual overnights:
- 52–103 nights/yr (1 night/wk average): 1/7 reduction (~14.3%)
- 104–155 nights/yr (2 nights/wk): 2/7 reduction (~28.6%)
- 156–174 nights/yr (3 nights/wk): 3/7 reduction (~42.9%)
- 175+ nights/yr (4+ nights/wk): 50% reduction plus extra £7/wk reduction
- Equal (or near-equal) shared care: liability may reduce to nil
Other Children in Paying Parent's Household
If the paying parent is supporting other biological or adopted children in their household, gross income is reduced before the CMS rate is applied:
- 1 other child: −11% reduction
- 2 other children: −14% reduction
- 3+ other children: −16% reduction
Worked Example — 2026
Gross £40,000/yr, 2 Children, 1 Night/Wk Shared Care
Paying parent earns £40,000/yr gross. Two qualifying children. 1 overnight per week with paying parent.
Official Sources & Legal References
- gov.uk — Calculate Child Maintenance (Official Tool)
- gov.uk — How Child Maintenance Is Worked Out
- Child Support Maintenance Calculation Regulations 2012
- DWP — Step-by-Step Guide to CMS Calculation
- NI Direct — Child Maintenance Rates (Northern Ireland)
- Commons Library Briefing — CMS Reform (October 2025)
Frequently Asked Questions
When to Consult a UK Family Law Solicitor
This calculator mirrors the official gov.uk CMS methodology, but legal advice is valuable if your case involves: above £3,000/wk gross (court top-up), self-employment with disputed income, significant capital or inheritance, international or cross-border enforcement, variations (special expenses, additional income), or shared-care disputes where the other parent contests overnight counts. Citizens Advice and the Money Helper offer free initial guidance.