UK Child Maintenance Calculation Rules: A Practical Guide for 2026/27
Around one in four separated families in the UK use the Child Maintenance Service (CMS) or its legacy predecessor the Child Support Agency to arrange payments, with many more agreeing amounts privately using the same statutory formula as a reference point. This pillar guide explains exactly how the CMS calculates maintenance in 2026/27: the gross income bands and percentage rates for one, two and three-or-more children, how shared care nights reduce the liability, how other children and multiple cases are handled, when a variation can change the income figure used, what counts as income, and what enforcement looks like when a paying parent falls behind.
The Child Maintenance Service applies a standard statutory formula to the paying parent's gross weekly income, usually obtained directly from HMRC records for the latest complete tax year rather than relying on self-reported figures. The calculation is largely mechanical: identify the correct rate type, apply the relevant percentage to the income within the applicable band, adjust for other children the paying parent supports, and reduce for any regular overnight shared care.
The CMS replaced the Child Support Agency (CSA) from 2012, with all CSA cases now transferred or closed. Both parents can apply for a calculation — usually the parent with main day-to-day care of the child — and an application fee may apply (waived in certain circumstances, including for applicants who have experienced domestic abuse).
Because the formula uses last year's recorded income, the CMS conducts periodic annual reviews to refresh the figure without either parent needing to reapply, and either parent can request an earlier recalculation if income has changed significantly (broadly, a change of 25% or more, or certain fixed triggers such as a change in benefits).
Rate Types and Percentages
There are five rate types depending on the paying parent's gross weekly income and circumstances:
Rate type
When it applies
Nil rate
Very low income, full-time student, under 16, prisoner or certain other circumstances
Flat rate
Low income (e.g. on certain benefits or very low earnings) — a fixed weekly amount
Reduced rate
Income just above the flat rate threshold — lower percentage plus a marginal amount
Basic rate
Most paying parents — 12% (1 child) / 16% (2 children) / 19% (3+ children) of gross weekly income in this band
Basic rate plus
Income above the basic rate ceiling — 9% / 12% / 15% on the portion above, added to the basic rate amount below it
The formula is capped at gross weekly income of £3,000 (£156,000 a year); above this the receiving parent can apply to court for a top-up order in addition to the CMS-calculated maximum, since the statutory formula does not extend further.
Shared Care Nights
Where the child stays overnight with the paying parent on a regular basis, the maintenance liability is reduced in bands based on average nights per year:
Nights per year
Reduction
52–103
1/7
104–155
2/7
156–174
3/7
175+ (broadly equal shared care)
1/2, plus flat-rate minimum removed
At 175 or more shared nights, care is considered close to equal and the flat-rate minimum no longer applies — depending on relative incomes, the calculated liability can fall to zero. Nights are agreed between the parents where possible; disputes are resolved by the CMS using evidence of the actual pattern over roughly the preceding 12 months.
Other Children and Multiple Cases
Before applying the main percentage, the CMS deducts a set percentage from the paying parent's gross income for any other children they are responsible for and living with (their own children from another relationship, or a partner's children they support), reflecting a higher deduction for more children in that household.
Where a paying parent has separate CMS cases for children with more than one former partner, the total percentage payable is calculated on the adjusted gross income and then divided proportionately across the cases by number of qualifying children in each, so the combined liability does not exceed the standard formula's overall percentage cap and no single receiving parent is short-changed relative to the others.
Variations
Either parent can apply for a variation where the standard HMRC-derived income figure does not reflect the true financial position. Common grounds include: additional income not captured by HMRC data, such as rental income or dividends above £2,500 a year; assets generating income disproportionate to declared earnings; a lifestyle inconsistent with reported income; the paying parent diverting income (for example, paying themselves a low salary from a company they control while the company retains profits); and the paying parent having unusually high costs, such as travel costs to maintain contact or the cost of supporting a disabled child.
The receiving parent can also apply for a variation if they believe the paying parent has understated income. Variations require supporting evidence and are assessed individually — the CMS does not automatically grant a variation just because one is requested.
What Counts as Income
Gross weekly income for the calculation generally includes employment earnings, self-employment profits, pension income and some taxable benefits, based on the most recent complete tax year HMRC holds. Certain means-tested benefits (Universal Credit, Income Support) and some disability-related payments are excluded from the income figure itself, though receiving only such benefits typically places the paying parent on the flat rate.
Unearned income such as dividends, rental income or savings interest above £2,500 a year is not automatically captured by the standard HMRC data feed and generally needs to be brought in through a variation application by the receiving parent if it is not already reflected.
Tax and Benefits Treatment
Child maintenance payments are not taxable income for the parent receiving them and are not tax-deductible for the parent paying them, whether arranged via the CMS or privately. Crucially, child maintenance received is disregarded when calculating Universal Credit and most other means-tested benefits — a deliberate policy design so that children do not lose out through reduced benefit entitlement because their parent also receives maintenance.
Enforcement of Missed Payments
Where payments are arranged through Collect and Pay and missed, the CMS has escalating powers: deduction from earnings orders requiring the employer to take maintenance directly from wages before payment; deduction orders against bank accounts, either a regular deduction or a one-off lump sum for arrears; and, for persistent serious non-payment, disqualification from holding a passport or driving licence, which requires a court application, or in the most extreme cases committal to prison.
Direct Pay cases (where parents arrange payment between themselves under a CMS calculation) can be switched to Collect and Pay if payments are repeatedly missed. Collect and Pay carries a 20% collection fee added to the paying parent's liability and a 4% fee deducted from what the receiving parent gets, which is part of why many parents prefer to keep arrangements on Direct Pay where trust allows.
How does the Child Maintenance Service calculate payments?
The CMS uses the paying parent's gross weekly income (from the most recent tax year HMRC holds, usually via a direct data link) and applies a percentage rate depending on the income band and number of qualifying children. There are five rate types: Nil rate (income too low or specific circumstances such as full-time students or under-16s), Flat rate (fixed weekly amount for very low incomes, such as those on certain benefits), Reduced rate (a lower percentage on income between the flat rate threshold and the basic rate threshold), Basic rate (the main rate applying to most paying parents), and Basic rate plus (a higher percentage tier for the portion of income above the standard basic rate ceiling). The calculation is entirely formula-driven — the CMS does not exercise discretion on the headline percentage, though variations can adjust the income figure used.
What are the basic rate percentages for 2026/27?
At the basic rate, the percentage of gross weekly income (between the lower and upper thresholds) payable as child maintenance is: 12% for one child, 16% for two children, and 19% for three or more children. For income above the basic rate ceiling (a higher weekly income threshold), the basic rate plus tier applies a reduced marginal percentage — 9% for one child, 12% for two children, and 15% for three or more children — on the portion of income above that ceiling, in addition to the basic rate amount on the income below it. The reduced rate (income just above the flat rate threshold) uses a lower initial percentage plus a marginal rate; the flat rate is a fixed low weekly amount irrespective of the number of children.
How is shared care factored into the calculation?
If the qualifying child stays overnight with the paying parent on a regular basis, the CMS applies a banded reduction to the maintenance amount, based on the average number of nights per year: 52-103 nights gives a 1/7 reduction, 104-155 nights gives a 2/7 reduction, 156-174 nights gives a 3/7 reduction, and 175 nights or more (broadly equal shared care) reduces the liability by 1/2 and removes the flat-rate minimum, meaning the paying parent could owe nothing if incomes and other factors balance out. Nights are usually based on an agreed pattern or, where disputed, on evidence over the previous 12 months. This reduction exists because the paying parent is directly covering costs during those nights rather than only contributing cash.
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What happens with multiple children from different relationships?
The CMS first adjusts the paying parent's gross income to account for any other children they are legally responsible for and living with (a percentage deduction depending on how many), then calculates maintenance for the qualifying children in the specific case using the adjusted income. Where a paying parent has child maintenance liabilities across more than one CMS case (for example, children with two different ex-partners), the total percentage due is calculated on the full adjusted income and then apportioned between the cases according to the number of qualifying children in each, so no single case receives more than its fair share of a capped total percentage.
Can the amount be varied from the standard calculation?
Yes, either parent can apply for a variation to adjust the income figure used, in defined circumstances: additional income not captured by HMRC data (such as rental income, dividends above a threshold, or unearned income over £2,500 a year); a lifestyle inconsistent with declared income (for example, driving an expensive car or living in an expensive property that does not match reported earnings); the paying parent has diverted income, such as by deliberately reducing salary or paying it into a company they control; or the paying parent has unusually high costs, such as travel to maintain contact with the child or supporting a disabled child or relative. Variations are decided case by case and require evidence; frivolous applications are typically rejected quickly.
What income counts and what is excluded?
Gross weekly income includes employment earnings, self-employment profits, pension income, and some benefits, generally taken from the most recent complete tax year on record with HMRC. Excluded from the standard calculation are means-tested benefits themselves (Universal Credit, Income Support), and some specific disability-related payments. The income figure is capped at £3,000 gross per week (£156,000 a year) for the standard formula — above that, the receiving parent must apply to court for a top-up order, since the CMS formula does not calculate maintenance on income above the cap.
Do child maintenance payments count as taxable income?
No. Child maintenance payments, whether arranged privately, through the CMS, or under a legacy Child Support Agency (CSA) case, are not taxable income for the receiving parent and are not tax-deductible for the paying parent. They also do not count as income for Universal Credit purposes in most cases — child maintenance received is generally disregarded when calculating means-tested benefit entitlement, unlike most other income types, which is a deliberate policy choice to avoid penalising children for the maintenance their parent receives.
What if the paying parent does not pay?
The CMS has escalating enforcement powers once payments through its Collect and Pay service are missed: deduction from earnings orders instructing the employer to deduct maintenance directly from wages; deduction orders against bank accounts, either regular or as a lump sum; disqualification from holding or obtaining a passport or driving licence in serious persistent cases, requiring a court application; and, in the most serious cases, committal to prison for wilful refusal to pay (rare, and only after all other routes have failed). Arrears continue to accrue and remain payable even where enforcement is delayed, and the CMS can pursue arrears for a considerable period after the case otherwise ends.
What is the difference between Direct Pay and Collect and Pay?
Direct Pay is a CMS calculation where the parents arrange payment directly between themselves (standing order or similar), with no CMS involvement in collection — used where parents can cooperate. Collect and Pay is where the CMS itself collects the money from the paying parent and passes it to the receiving parent, used where there is a history of non-payment or parents cannot communicate; it carries a collection fee of 20% added to the paying parent's liability and a 4% fee deducted from the receiving parent's payment. Either party can request a switch between the two if circumstances change, such as repeated missed payments under Direct Pay.
How does the calculation change as children grow up?
Child maintenance is payable for a qualifying child up to age 16, or up to age 20 if the child remains in full-time non-advanced education (broadly, A-levels or equivalent, not university). Once the youngest qualifying child leaves this bracket, the CMS case closes automatically. Either parent can apply for a fresh calculation at any point if circumstances materially change — a significant change in either parent's income, a change in shared care nights, or the birth of additional children affecting the paying parent's other-child deduction. The CMS also conducts periodic reviews roughly annually to update the calculation to the latest available income data without either parent needing to apply.
Disclaimer: Child maintenance rules and thresholds are reviewed periodically. Figures here reflect the position in 2026/27. Always check gov.uk or the Child Maintenance Service directly for your specific circumstances.
