How does the CMS calculate child maintenance payments?

The CMS uses a formula based on the paying parent's gross annual income, the number of children, and how many nights per year the children stay with the paying parent. The basic rate is 12% of gross weekly income for one child, 16% for two children, and 19% for three or more children — all before tax and National Insurance.

What is the difference between Direct Pay and Collect and Pay?

Under Direct Pay, the CMS calculates the amount but parents arrange payments between themselves — the CMS does not collect money. Under Collect and Pay, the CMS collects payments from the paying parent and passes them to the receiving parent, but the paying parent pays an additional 20% collection fee, and the receiving parent pays a 4% deduction from each payment.

What if the paying parent's income changes?

If the paying parent's income changes by 25% or more, either parent can ask the CMS to recalculate the maintenance amount. The CMS reviews the calculation using the latest income information from HMRC. Changes of less than 25% do not automatically trigger a reassessment.

How do overnight stays affect child maintenance?

The CMS reduces the child maintenance calculation by 1/7 for each night the child stays with the paying parent, averaged over a year. If the paying parent has shared care on average 52–103 nights per year, the amount is reduced by 1/7. For 104–155 nights, it is reduced by 2/7. For 156–174 nights, it is reduced by 3/7. If care is exactly equal (175+ nights), no maintenance may be payable.

What is the CMS application fee in 2026?

As of 2026, the CMS application fee is £20. This applies unless the applicant is a victim of domestic abuse (in which case the fee is waived), under 18, or applying under certain other exemption categories. Both parents can also agree a family-based arrangement instead — which costs nothing and keeps the arrangement informal.

Child Maintenance Service (CMS): How Payments Are Calculated 2026

When parents separate, the non-resident parent (the one the children do not live with most of the time) is legally required to contribute towards the children's living costs. The Child Maintenance Service (CMS) is the government body that calculates, collects, and enforces child maintenance in the UK. Understanding how the CMS works out what you should pay or receive can help you plan your finances — and avoid surprises.

What Is the Child Maintenance Service?

The CMS replaced the Child Support Agency (CSA) and is run by the Department for Work and Pensions (DWP). It applies to children under 16, or under 20 if they are in full-time secondary education (up to A-levels or equivalent). The CMS covers England, Scotland, and Wales. Northern Ireland has a separate but similar Child Maintenance Service.

The CMS is not the only option. Parents can agree a "family-based arrangement" privately without involving the CMS at all — this is free, flexible, and by far the most common approach. The CMS steps in only when parents cannot agree, or when one parent requests its involvement.

The Five CMS Rates and How Your Payment Is Calculated

The CMS calculates child maintenance using the paying parent's gross annual income (from HMRC records, usually the latest tax year available) and applies one of five rates:

1. Nil Rate

If the paying parent's gross weekly income is below £7, no maintenance is payable. This applies, for example, to a parent on certain benefits or with no income. They may still be required to pay a flat rate in some circumstances — the CMS will clarify which rate applies.

2. Flat Rate

If the paying parent's gross weekly income is between £7 and £100 (or they are receiving certain benefits such as Income Support or Jobseeker's Allowance), they pay a flat rate of £7 per week. This amount stays the same regardless of how many children there are.

3. Reduced Rate

For gross weekly income between £100 and £200, a reduced rate applies. The calculation is more complex: the paying parent pays a percentage of the first £100 of income plus a lower percentage of income between £100 and £200. This is intended to ensure parents on lower incomes still contribute but are not pushed into hardship.

4. Basic Rate

This is the most common rate. It applies to gross weekly income between £200 and £800. The percentages are:

12% of gross weekly income for 1 child
16% of gross weekly income for 2 children
19% of gross weekly income for 3 or more children

For example, a paying parent earning £35,000 a year (roughly £673 per week) with two children would pay 16% of £673 = £107.68 per week, or about £467 per month.

5. Basic Plus Rate

For gross weekly income above £800 (up to £3,000), the same percentages apply to the first £800. For income between £800 and £3,000 per week, an additional percentage applies. The CMS does not consider income above £3,000 per week. For very high earners, the receiving parent can apply to the court for a "top-up" maintenance order under Schedule 1 of the Children Act 1989 — this is separate from the CMS.

How Overnight Stays Reduce the Amount

The CMS recognises that if the paying parent has the children overnight, they are already contributing directly to the children's costs through food, utilities, and other expenses. The maintenance amount is therefore reduced based on the average number of nights per year:

52–103 nights per year: Reduced by 1/7 (about 14%)
104–155 nights per year: Reduced by 2/7 (about 28%)
156–174 nights per year: Reduced by 3/7 (about 43%)
175+ nights per year (shared care): Maintenance may not be payable at all — the CMS treats both parents as having equal day-to-day care

These bands apply regardless of how many children are involved. It is the total number of nights averaged across all qualifying children that determines the reduction.

Direct Pay vs Collect and Pay — the Cost Difference

Once the CMS calculates the amount, there are two ways payments can be handled:

Direct Pay: The CMS tells both parents the amount but does not handle the money. Parents arrange payments between themselves. There is no CMS fee on top.
Collect and Pay: The CMS collects payment from the paying parent and sends it to the receiving parent. The paying parent is charged an additional 20% collection fee on top of the maintenance amount. The receiving parent has a 4% deduction taken from each payment before they receive it. So on a £400 monthly payment, the paying parent pays £480 and the receiving parent receives £384.

Collect and Pay is used when the paying parent has a history of non-payment, or when Direct Pay breaks down. The CMS can also take enforcement action including deducting earnings directly from wages, seizing assets, or even revoking a driving licence or passport in persistent non-compliance cases.

When the Calculation Can Change

Child maintenance is not fixed forever. Either parent can ask the CMS to review the calculation if:

The paying parent's income changes by 25% or more (up or down)
The number of overnight stays changes and crosses one of the band thresholds
A child leaves full-time secondary education or the arrangement ends for another qualifying reason
A new child is included in the calculation (for example, the paying parent has another child in their household)

The CMS normally reviews the calculation annually, based on the latest HMRC data. If the income has changed but by less than 25%, the existing calculation stays in place until the annual review.

What If the Paying Parent Lives Abroad?

The CMS can enforce child maintenance against a paying parent who lives abroad if the UK has a reciprocal enforcement agreement with that country. This includes most EU countries, the US, Canada, Australia, New Zealand, and many others. The CMS works with the foreign country's child maintenance authority to calculate and collect payments. This is handled by the CMS's international case team (Remo Unit). Enforcement abroad can take significantly longer than domestic cases.

FAQ

Can we avoid the CMS altogether?

Yes. A family-based arrangement is by far the most common approach. Parents agree the amount, frequency, and method of payment between themselves — it can include direct transfers, buying school uniforms, or paying for clubs and activities. There is no CMS fee, no government involvement, and it can be changed by agreement at any time. If it later breaks down, either parent can apply to the CMS. The CMS encourages parents to try a family-based arrangement first — the £20 application fee is partly designed to incentivise this.

What if the paying parent hides income or is self-employed?

The CMS uses HMRC data — so if income is declared to HMRC, the CMS can see it. However, self-employed parents sometimes reduce their declared income through business expenses, dividends, or other arrangements. If the receiving parent believes the paying parent is hiding income, they can ask the CMS to apply a "variation" — for example, treating assets or a lifestyle inconsistent with declared income as evidence of hidden resources. The CMS has investigation powers and can refer cases to its Financial Investigations Unit.

Does remarriage or a new partner affect child maintenance?

No. The CMS calculation is based on the paying parent's income only, not on their new partner's income (or the receiving parent's new partner's income). However, if the paying parent has children in a new household, they may be able to apply for a reduction in the amount payable — the CMS applies a formula that reduces the income used in the calculation to account for other dependent children living with the paying parent.

What if I disagree with the CMS calculation?

You can ask the CMS for a mandatory reconsideration within one month of the decision. If you are still dissatisfied, you can appeal to the First-tier Tribunal (Social Security and Child Support). You should provide evidence to support your position. You can have a representative, including a solicitor or Citizens Advice adviser, help you through the appeals process.

Authoritative Sources

GOV.UK — Calculate your child maintenance — official calculator tool
GOV.UK — Child Maintenance Service overview
Child Support Act 1991 — the primary legislation
Child Maintenance Options — government-supported service for family-based arrangements
Citizens Advice — Child maintenance
Gingerbread — charity for single-parent families

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