Child Maintenance (CMS): How the UK Rates Are Worked Out

When parents separate, most child maintenance in England, Wales and Scotland is not agreed privately but worked out by the Child Maintenance Service (CMS) using a statutory formula based on the paying parent's gross weekly income, taken directly from HMRC records.

What Is Child Maintenance and Who Pays It?

Child maintenance is regular financial support paid by a parent who does not have main day-to-day care of a child to the parent (or other person) who does, to help with the child's everyday living costs. It applies whether or not the parents were ever married, and it is separate from any wider financial settlement on divorce. Most parents in England, Wales and Scotland who cannot agree maintenance privately use the Child Maintenance Service, a government body that assesses and, if needed, enforces payment. The CMS is not a court, and it is not the same as spousal maintenance. Parents remain free to agree their own arrangement without involving the CMS, but if they cannot agree, or an arrangement breaks down, either parent can apply for a statutory CMS calculation, which is legally binding once made.

How the CMS Works Out Gross Weekly Income

The CMS calculation starts from the paying parent's gross weekly income, meaning income before tax and National Insurance are deducted, but after deducting contributions to an occupational or personal pension. This figure normally comes directly from HMRC's records for the most recent tax year, rather than payslips supplied by either parent, which is intended to reduce disputes over the starting figure. The CMS then applies one of five rates to that gross weekly income to reach a base weekly maintenance amount, before any further adjustment for other children in the paying parent's household or for shared overnight care. Only after all of those steps is the final weekly liability set.

The Five CMS Rate Bands

Which of the five rates applies depends entirely on the paying parent's gross weekly income, as shown below.

Income above £3,000 a week is disregarded entirely by this formula. A receiving parent who believes the paying parent's true resources are higher can apply to a court for an additional top-up order, but that sits outside the CMS calculation.

Basic and Basic Plus Rates by Number of Children

At the Basic rate (gross weekly income £200 to £800), the percentage charged rises with the number of qualifying children: 12% for one child, 16% for two children, and 19% for three or more. At Basic Plus (the slice of income between £800.01 and £3,000), a lower percentage applies to that additional slice: 9% for one child, 12% for two children, and 15% for three or more, on top of the Basic-rate amount already charged on the first £800. So a Basic Plus liability is calculated in two parts and then added together, not as a single percentage of the whole income.

The Reduced Rate

Between £100.01 and £199.99 of gross weekly income, the paying parent owes a flat £7 plus a percentage of the income above £100: 17% for one child, 25% for two children, or 31% for three or more, where the paying parent has no other relevant children. Where the paying parent does have other children living with them, this percentage reduces further under the same statutory rules that apply to the Basic and Basic Plus reductions below, which adds complexity at this band that a simple calculator cannot always capture in full.

Other Children Living With the Paying Parent

If the paying parent (or their partner) receives Child Benefit for other children living in their household, the CMS reduces the gross weekly income figure before applying the Basic or Basic Plus rate: by 11% for one other child, 14% for two other children, or 16% for three or more other children. This reduction happens before the rate band percentage is applied, so it lowers the base figure the percentage is calculated from, not the final maintenance amount directly.

Shared Care: How Overnight Stays Reduce the Amount

Where a qualifying child stays overnight with the paying parent, the weekly maintenance for that child is reduced according to how many nights a year that happens: a deduction of one-seventh for 52 to 103 nights a year, two-sevenths for 104 to 155 nights, three-sevenths for 156 to 174 nights, and one-half for 175 nights or more, with a further flat £7 a week taken off (shared across the children involved) once the child stays half the year or more. Where the Flat rate applies because the paying parent is on a prescribed benefit, any amount of shared care reduces that liability to nil; where the Flat rate applies purely because of low income, the £7 stays payable regardless of shared care.

Direct Pay vs Collect and Pay

Once the CMS has calculated the maintenance, parents choose, or are moved onto, one of two payment routes. Direct Pay means the CMS tells both parents the calculated amount and the parents arrange the actual transfers between themselves, with no fee for either side. Collect and Pay means the CMS itself collects the money from the paying parent and passes it to the receiving parent, which carries a collection fee: 20% on top of the maintenance amount for the paying parent, and 4% deducted from what the receiving parent gets. Collect and Pay is typically used where there is a history of missed payments or where one parent does not want direct contact with the other.

Applying to the Child Maintenance Service

Applying to the CMS is free for everyone. The one-off £20 application fee that used to apply was abolished in Great Britain from 26 February 2024, under the Child Support (Management of Payments and Arrears and Fees) (Amendment) Regulations 2024 (SI 2024/87). Beyond making the application itself, only the ongoing Collect and Pay percentages set out above apply; there is no separate charge simply for having a case calculated.

Northern Ireland: A Separate but Mirrored Scheme

Child maintenance in Northern Ireland is not handled by the same CMS as Great Britain. Northern Ireland has its own Child Maintenance Service, run by the Department for Communities, operating under its own legislation. In practice, the rates, bands, other-children reduction, shared-care bands, and Direct Pay and Collect and Pay fees all mirror the scheme used in England, Wales and Scotland. Applying to the Northern Ireland Child Maintenance Service is free too; Northern Ireland separately abolished its own £20 application fee from 18 January 2024. A parent in Northern Ireland applies through the Northern Ireland Child Maintenance Service rather than the GB service, but should expect the same calculation to apply to their case.

For a worked example of what a specific income and family situation might actually mean in pounds, see how much child maintenance you might pay or get, or use our child maintenance calculator to run the statutory formula against your own figures. If you were never married to the other parent, cohabiting couples' rights explains how that differs from child maintenance. Child maintenance also continues to apply during and after a divorce, separately from any financial settlement. For the full picture across nations, see our UK family law hub, part of our wider guide to United Kingdom law.

This article explains how the Child Maintenance Service formula works in general terms; it is not legal or financial advice, and it is not a substitute for a CMS calculation. Only the CMS can make a binding assessment for a particular family, and any figures here are estimates only. If you need to apply, or you disagree with an existing calculation, contact the Child Maintenance Service directly, or get free guidance from Child Maintenance Options, Gingerbread or Citizens Advice. Family separation is difficult for everyone involved, and support is available regardless of which parent you are.