UK Child Maintenance Calculator 2026
Estimate child maintenance using the Child Maintenance Service (CMS) formula — 5 income bands, shared care overnight reductions, and benefit flat-rate rules, all based on the paying parent's gross weekly income.
By Sammy S. · Founder · AuthorUpdated for 2026
Estimates only — not legal advice. CMS makes final determinations. Consult a family law solicitor.
Child Support Calculator
Enter details to estimate payments
CMS formula based on gross weekly income. Shared care reduces payments.
Parent A's custody %. Parent B calculated automatically.
United Kingdom · CMS Formula
Estimated Child Maintenance
Weekly
£83
Biweekly
£166
Monthly
£360
Annual
£4,320
Income & custody split
Calculation breakdown
State details
Guideline: Child Maintenance Service (CMS) Rules
Updated: 2026 · Official source
Recalculate if income changes by about 15–20% or more.
Shared custody can lower the paying parent's obligation.
This is an estimate only — courts make the final order.
Child support is generally not tax deductible or taxable income.
Add-ons like childcare, insurance, or medical costs can raise the total.
High-income cases above guideline caps often use court discretion.
Verify amounts with the official calculator for your location.
Consider a family law professional before relying on any estimate.
Estimate only — not a court order.
CMS rate bands 2026
Children percentages: 12% (1 child) · 16% (2) · 19% (3+)
Shared care reductions
Minimum payment: £7/week regardless of reductions.
Other countries
2026 CMS child maintenance reference table
Weekly amounts for common gross weekly incomes — no shared care, no other children. Source: gov.uk/how-child-maintenance-is-worked-out
| Gross weekly income | Rate band | 1 child | 2 children | 3+ children |
|---|---|---|---|---|
| £150/wk | Reduced | £16.50 | £20.50 | £23.50 |
| £200/wk | Basic | £24.00 | £32.00 | £38.00 |
| £300/wk | Basic | £36.00 | £48.00 | £57.00 |
| £500/wk | Basic | £60.00 | £80.00 | £95.00 |
| £800/wk | Basic | £96.00 | £128.00 | £152.00 |
| £1,000/wk | Basic Plus | £114.00 | £152.00 | £182.00 |
| £2,000/wk | Basic Plus | £204.00 | £272.00 | £332.00 |
| £3,000/wk | Basic Plus | £294.00 | £392.00 | £482.00 |
How the CMS formula really works — and why gross income matters
The UK's Child Maintenance Service doesn't use net take-home pay — it uses gross weekly income obtained directly from HMRC records. This matters because two parents who take home the same amount after tax can have very different gross figures if one has a salary sacrifice pension, for example. The CMS uses the gross, not the net, and adjustments for pension contributions are limited.
The rate bands are designed to protect low earners while maintaining a percentage-based system for most incomes. The flat rate of £7/week applies both to those on qualifying benefits and to anyone with gross weekly income between £7 and £100. This means a parent earning £5,000/year pays the same flat rate as one on Universal Credit — which reflects a policy choice, not an arithmetic one.
Basic rate examples — 2 children at 16%
Shared care reductions — overnight stays count, not daytime hours
The CMS bases shared care reductions entirely on overnight stays, not daytime care or school pickups. A parent who has the child every weekend but doesn't have overnight stays doesn't get a reduction at all; one who has 52 nights gets 1/7th off. The threshold system works in bands:
Note that the minimum payment stays at £7/week no matter how high the reduction. For parents close to a threshold, keeping accurate overnight stay records matters — moving from 103 to 104 nights shifts the reduction from 1/7 to 2/7.
Using the CMS vs family-based arrangements — what most parents don't know
Many parents settle child maintenance privately without involving the CMS, which is entirely free. Where the CMS is used, Direct Pay is also free — the CMS calculates the amount but parents arrange payment themselves. The Collect & Pay service charges fees: a 20% surcharge is added to the paying parent's liability, and 4% is deducted from each payment passed to the receiving parent. The £20 application fee was abolished in February 2024. If parents are on reasonable terms, a private arrangement using the CMS formula costs nothing and avoids these charges.
However, the CMS has strong enforcement powers for non-payment: deduction from earnings orders, deduction from bank accounts, charging orders against property, and in serious cases, imprisonment. Annual reviews use HMRC's latest tax data automatically; either parent can also request a reassessment if income changes by 25% or more during the year.
Key distinction: The CMS only calculates basic maintenance. It does not cover additional expenses like school fees, extra-curricular activities, or medical costs. These require a separate court order or private agreement — unlike Canada's Section 7 expenses or the US income shares model, the CMS formula makes no provision for these extras.