How Much Child Maintenance Will I Pay or Get?

How much child maintenance you pay or get depends on the paying parent's gross weekly income, how many qualifying children there are, any overnight shared care, and any other children they support. This page works through the Child Maintenance Service formula step by step, with worked examples across every rate band.

How the Amount Is Worked Out

The Child Maintenance Service (CMS) uses a statutory formula set out in the Child Support Maintenance Calculation Regulations 2012 to turn the paying parent's income into a weekly maintenance figure. The same formula applies across England, Wales and Scotland; Northern Ireland runs its own Child Maintenance Service under separate legislation that mirrors the same rates and bands (see the Northern Ireland section below).

The calculation runs in a fixed order: work out gross weekly income, reduce it for any relevant other children, apply the rate band for that income level and the number of qualifying children, then reduce the result for any overnight shared care. For the wider picture of who has to pay, how payments are collected and the application fee, see the child maintenance page. This page focuses only on how much is likely to be due at each stage.

Step 1: Gross Weekly Income

Gross weekly income is the paying parent's income before Income Tax and National Insurance are deducted, but after any contributions to an approved occupational or personal pension scheme. The CMS normally obtains this figure directly from HM Revenue and Customs records for the most recent tax year, then converts it to a weekly amount.

Income above £3,000 a week is ignored by the statutory formula. If the paying parent's gross weekly income is higher than that, the receiving parent can apply to court for an additional "top-up" order to cover income above the CMS ceiling; the CMS itself only ever calculates on the first £3,000.

The Five Rates

The CMS applies one of five rates depending on gross weekly income.

The percentages used within each rate depend on the number of qualifying children:

• Basic rate (£200 to £800): 1 child 12%, 2 children 16%, 3 or more children 19%.
• Basic Plus (the slice between £800.01 and £3,000): 1 child 9%, 2 children 12%, 3 or more children 15%.
• Reduced rate (£100.01 to £199.99): £7 plus 17% (1 child), 25% (2 children) or 31% (3 or more children) of the income above £100. These reduced-rate percentages are for a paying parent with no relevant other children; the calculation gets more complex where other children are also involved at the reduced rate.

Worked Examples

These examples show how the formula produces a weekly figure at each rate band. They are illustrations of the statutory formula, not a prediction of what any specific parent will pay or receive; results are shown to the nearest penny.

Example 1: Basic rate, two children, no shared care

1. Gross weekly income is £600, which falls in the basic-rate band (£200 to £800).
2. There are 2 qualifying children, so the basic-rate percentage is 16%.
3. 16% of £600 = £96.
4. There is no overnight shared care, so no further reduction applies.
5. Weekly amount: £96.

Example 2: Basic rate, one child, with shared care

1. Gross weekly income is £600, again in the basic-rate band.
2. There is 1 qualifying child, so the basic-rate percentage is 12%.
3. 12% of £600 = £72.
4. The child stays overnight with the paying parent for 52 to 103 nights a year, which reduces the amount by 1/7: £72 minus (£72 divided by 7, or £10.29) = £61.71.
5. Weekly amount: £61.71.

Example 3: Basic Plus, two children

1. Gross weekly income is £1,000, which is above £800, so the Basic Plus rate applies.
2. The basic-rate percentage for 2 children (16%) applies to the first £800: 16% of £800 = £128.
3. The Basic Plus percentage for 2 children (12%) applies to the remaining £200 (£1,000 minus £800): 12% of £200 = £24.
4. Add the two parts together: £128 plus £24 = £152.
5. Weekly amount: £152.

Example 4: Reduced rate, one child

1. Gross weekly income is £150, which falls in the reduced-rate band (£100.01 to £199.99).
2. The flat £7 applies first.
3. Add 17% of the income over £100: £150 minus £100 = £50, and 17% of £50 = £8.50.
4. Add the two parts: £7 plus £8.50 = £15.50.
5. Weekly amount: £15.50.

Example 5: Basic rate with a relevant other child

1. Gross weekly income is £500, in the basic-rate band, for 2 qualifying children.
2. The paying parent has 1 other child living with them (a child they or their partner get Child Benefit for), so their income is reduced by 11% before the rate is applied: £500 minus 11% (£55) = £445.
3. The basic-rate percentage for 2 children (16%) is then applied to the reduced figure: 16% of £445 = £71.20.
4. Weekly amount: £71.20.

Example 6: Flat rate A paying parent with gross weekly income of £75 falls in the flat-rate band (£7 to £100) and pays a flat £7 a week, regardless of exactly where their income sits within that band or how many qualifying children there are. The same £7 flat rate also applies where the paying parent is receiving certain benefits, whatever their reported income.

Example 7: Nil rate A paying parent with gross weekly income under £7 a week is assessed at the nil rate and pays nothing. The nil rate can also apply in certain other circumstances set out in the regulations, such as where the paying parent is a full-time student, in prison, or is themselves a child under 16.

The table below summarises the worked examples above.

Shared Care: How Overnight Nights Reduce the Amount

If a qualifying child stays overnight with the paying parent for at least 52 nights a year, on average one night a week, the weekly amount worked out under the flat, reduced, basic or basic-plus rate is reduced. The more nights the child spends with the paying parent, the bigger the reduction, and the reduction is applied separately for each qualifying child's own care pattern.

Shared care only reduces amounts due under the flat, reduced, basic or basic-plus rates. Where the flat rate is being paid because the paying parent is on certain prescribed benefits, shared care of any qualifying amount can reduce that flat rate to nil; where the flat rate applies because of low income rather than benefits, it stays at £7 regardless of shared care.

Other Children in the Paying Parent's Home

If the paying parent, or their partner, gets Child Benefit for other children living in their household, their gross weekly income is reduced before the basic or basic-plus rate is applied. The reduction depends on how many other children there are: 11% for one other child, 14% for two, or 16% for three or more. This reduction happens before the rate band and percentage for the actual qualifying children are applied, as shown in Example 5 above.

This "relevant other children" reduction only applies at the basic and basic-plus rates. The reduced rate has its own, more complex treatment where other children are also involved, which is beyond the scope of the figures set out on this page.

This Is an Estimate, Not a Binding Calculation

Every figure on this page is a worked example of the statutory formula, using illustrative income and children figures to show the mechanics of the calculation. A real CMS assessment depends on verified HMRC income data, the specific number of qualifying and relevant other children, the actual shared-care pattern, and any variations the CMS applies for the paying parent's particular circumstances.

Only the Child Maintenance Service can produce a binding calculation for an individual case. For an estimate based on your own figures, use the child maintenance calculator, which applies this same formula; it is an estimate only, and the CMS's own assessment is what actually determines the amount due. Child maintenance is due whether the parents were married, cohabiting or never lived together at all; separating cohabiting parents' other legal rights are covered separately on the cohabiting couples' rights page.

Northern Ireland

Northern Ireland has its own Child Maintenance Service, run by the Department for Communities rather than the Great Britain Child Maintenance Service. It applies the same 2012 statutory formula in substance: the same five rates, the same basic and basic-plus percentages, the same shared-care bands, and the same relevant-other-children reduction described above. Anyone in Northern Ireland working out likely child maintenance can use the figures and examples on this page; contact NI's Child Maintenance Service or Child Maintenance Choices for case-specific help.

Use the Child Maintenance Calculator

To apply this formula to your own income, number of children, shared care and other children, use the UK child maintenance calculator, which mirrors the rates, bands and reductions set out on this page and shows its full working. It gives an estimate only; the Child Maintenance Service makes the binding calculation. For the full picture of how child maintenance applications, payment methods and fees work, see the child maintenance page, the UK family law hub, and the United Kingdom country hub.

This page explains how the Child Maintenance Service's statutory formula works and is general information, not legal or financial advice. It is not a substitute for an actual CMS calculation, which is based on verified income data and the specific facts of a case. For a personalised estimate use the child maintenance calculator, and for free, impartial support contact the Child Maintenance Service, Child Maintenance Options or Gingerbread.