Child Maintenance Calculator UK (CMS) 2026
The statutory amount, worked out the same way the Child Maintenance Service does.
Estimate child maintenance under the Child Maintenance Service (CMS) 2012 formula — from the paying parent's gross weekly income, the number of children, any other children in their household and shared-care overnight stays. See it weekly, monthly and yearly, with Collect & Pay fees on top.
Statutory CMS formula (2012 scheme), rates checked July 2026. Estimates only — the official calculator at gov.uk/calculate-child-maintenance is definitive.
How the Child Maintenance Service works out the amount
Start with gross weekly income
The CMS starts from the paying parent's gross income — before Income Tax and National Insurance, but after occupational or personal pension contributions. It normally takes the most recent annual figure held by HMRC, divides it by 365 and multiplies by 7. £42,000 a year becomes £805.48 a week. The receiving parent's income is never part of the calculation.
Then apply one of five rates
Income under £7 a week pays nothing (nil rate). £7–£100, or certain benefits, pays the £7 flat rate. £100.01–£199.99 uses the reduced rate. £200–£800 uses the basic rate — 12% for 1 child, 16% for 2, 19% for 3 or more — and income between £800.01 and £3,000 adds a basic plus slice of 9%, 12% or 15% on the amount over £800. On £805.48 for 2 children that is 16% of £800 plus 12% of £5.48: £128.66 a week, about £558 a month.
Finally, adjust
Other children living in the paying parent's household reduce assessed income by 11%, 14% or 16% before the rate is applied, and overnight stays of 52 nights a year or more cut the result by 1/7, 2/7, 3/7 or half. This calculator applies every step in the same order, so the figure you see traces exactly to the GOV.UK rules.
Rates table and worked weekly amounts
| Gross weekly income | Rate | 1 child | 2 children | 3+ children |
|---|---|---|---|---|
| Under £7 | Nil | £0 | £0 | £0 |
| £7–£100 or on benefits | Flat | £7 a week in total | ||
| £100.01–£199.99 | Reduced | £7 + 17% over £100 | £7 + 25% over £100 | £7 + 31% over £100 |
| £200–£800 | Basic | 12% | 16% | 19% |
| £800.01–£3,000 | Basic plus | +9% over £800 | +12% over £800 | +15% over £800 |
What that produces, with no other children or shared care:
| Gross weekly income | 1 child | 2 children | 3+ children |
|---|---|---|---|
| £150 | £15.50 | £19.50 | £22.50 |
| £250 | £30.00 | £40.00 | £47.50 |
| £400 | £48.00 | £64.00 | £76.00 |
| £600 | £72.00 | £96.00 | £114.00 |
| £800 | £96.00 | £128.00 | £152.00 |
| £1,200 | £132.00 | £176.00 | £212.00 |
| £2,000 | £204.00 | £272.00 | £332.00 |
| £3,000 (cap) | £294.00 | £392.00 | £482.00 |
These rates have been fixed in the 2012 scheme rules since it launched — they do not change with the tax year, though the income figure the CMS uses refreshes annually from HMRC records.
The adjustments people miss
Other children in the paying parent's household — their own children or stepchildren they get Child Benefit for — reduce assessed income before the rate is applied: by 11% for one, 14% for two, 16% for three or more. On £805.48 a week, one other child brings the assessed figure to £716.88, and the 2-child amount from £128.66 down to £114.70. On the reduced rate the same principle applies through lower percentages (for example 14.1% instead of 17% for one child with one other child at home).
Pension contributions come off before anything else — paying into an occupational or personal pension lowers the assessed income pound for pound. Above £3,000 a week the formula stops counting income; the receiving parent can apply to the courts for a top-up order beyond the capped amount. If income has changed by 25% or more from the HMRC figure, either parent can ask the CMS to use current income instead.
Family-based, Direct Pay or Collect & Pay
The formula is the same however you arrange payment — the cost of the arrangement is not. A family-based arrangement is a private agreement: free, flexible, nothing to apply for, and many parents simply use the statutory figure as a neutral starting point. Direct Pay means the CMS calculates the amount but parents pay each other directly — no collection fees. Collect & Pay, where the CMS collects and passes payments on, adds 20% to what the paying parent pays and deducts 4% from what the receiving parent gets: £96.00 a week becomes £115.20 out and £92.16 in, £23.04 a week absorbed in fees.
In June 2025 the government announced plans to abolish Direct Pay and charge compliant parents on Collect & Pay 2% each from 2027-28 (non-compliant payers would still face 20%) — until that takes effect, the 20%/4% fees stand. Missed payments on Collect & Pay can also trigger enforcement charges, and the CMS can deduct maintenance straight from earnings or benefits.
❓ Frequently asked Frequently asked questions
How is child maintenance calculated in the UK?
The Child Maintenance Service works from the paying parent's gross weekly income. Example: £42,000 a year is £805.48 a week (annual income ÷ 365 × 7). One other child living with the paying parent reduces assessed income by 11% to £716.88. The basic rate for 2 children is 16%, giving £114.70. Shared care of 52–103 nights a year cuts it by 1/7 to £98.31 a week — about £426 a month.
What is a CSA calculator?
The Child Support Agency (CSA) was replaced by the Child Maintenance Service (CMS) in 2012, and the last CSA cases closed in 2018 — but many people still search for a CSA calculator. This calculator applies the current CMS 2012-scheme formula, which uses gross rather than net income.
Is child maintenance based on gross or net income?
Gross — income before Income Tax and National Insurance are taken off, but after occupational or personal pension contributions are deducted. The CMS normally uses the latest annual figure held by HMRC, divided by 365 and multiplied by 7 to get a weekly amount.
What if the paying parent is on benefits?
The flat rate of £7 a week applies if the paying parent receives certain benefits, or has gross weekly income between £7 and £100. Below £7 a week — or if the paying parent is a student in full-time non-advanced education, in prison, or under 16 — the nil rate applies and nothing is due under the formula.
How do overnight stays reduce child maintenance?
On the reduced and basic rates, maintenance falls by 1/7 for 52–103 nights a year with the paying parent, 2/7 for 104–155 nights, and 3/7 for 156–174 nights. At 175 nights or more it is halved, with a further £7 a week off per child. On those rates the paying parent still pays at least £7 a week — but if the payer is on the benefits flat rate, 52 nights or more means no maintenance is due for the child who stays overnight.
When does child maintenance stop?
Usually when the child turns 16, or up to 20 if they stay in approved full-time non-advanced education or training — A-levels or equivalent, broadly for as long as Child Benefit remains payable for them. Parents can agree to continue support beyond that privately.
What happens if the paying parent earns over £3,000 a week?
The statutory formula ignores gross income above £3,000 a week. At the cap the maximum formula amounts are £294 a week for 1 child, £392 for 2 and £482 for 3 or more (before adjustments). The receiving parent can apply to the courts for a top-up order above the cap.
Can parents agree child maintenance privately?
Yes. A family-based arrangement is free, flexible and can be changed whenever both parents agree — no CMS involvement at all. Many parents use the statutory formula as a neutral starting point for that conversation. If you want the CMS to calculate but pay each other directly, Direct Pay has no collection fees either.
What are the Collect and Pay fees?
When the CMS collects and passes on payments, the paying parent pays 20% on top of the maintenance and the receiving parent has 4% deducted. On £96.00 a week the payer hands over £115.20 and the receiver gets £92.16. In June 2025 the government announced plans to move to a 2% fee for each parent from 2027-28 for compliant cases.
Does the receiving parent's income affect child maintenance?
No. The statutory formula looks only at the paying parent's gross income, the number of children maintenance is for, other children living in the paying parent's household, and shared-care nights. The receiving parent's income never changes the figure.
Where these figures come from
Every rate, band and fee comes from GOV.UK — the source of record for the Child Maintenance Service.
- The five rates, income bands and shared-care reductions — GOV.UK — How child maintenance is worked out.
- Exact percentages, other-children reductions and gross income definition — GOV.UK — How we work out child maintenance (CMSB012).
- Collect & Pay fees (20% payer / 4% receiver) and Direct Pay — GOV.UK — Child Maintenance Service.
- The official calculator — GOV.UK — Calculate your child maintenance. This page is an estimate of the statutory formula; the official calculator and a CMS assessment are definitive.
Last checked: July 2026. The 2012-scheme rates are unchanged since introduction; the June 2025 announcement of 2% Collect & Pay fees from 2027-28 has not yet taken effect.
Select the question that matches where you are right now.
Your result is the weekly amount the statutory CMS formula produces for your circumstances — the figure a CMS assessment would be built around, and the neutral reference point for any private conversation.
Use it as common ground. Both parents running the same formula from the same income figure removes most of the argument — the monthly equivalent is usually the number budgets are built on.
Not a CMS decision. An actual assessment uses the income HMRC reports, verified shared-care nights and any variations — and only the official GOV.UK calculator and the CMS itself are definitive.
The 2012-scheme rates, reductions and the £3,000 cap as published on GOV.UK, checked July 2026. All calculations run in your browser — nothing is stored or sent.
Four inputs move the figure far more than people expect.
The formula runs on income before tax and NI — but after pension contributions. Using the take-home figure understates maintenance badly; using pre-pension income overstates it.
One night a week is a 1/7 cut; three nights is 3/7. Counting nights honestly — and evidencing them — matters more than almost any other input.
Children the paying parent supports at home reduce assessed income by 11–16% before the rate applies — a step private negotiations often forget entirely.
The CMS uses the latest figure HMRC holds, which can lag a pay rise or a redundancy by many months. If current income differs by 25% or more, either parent can ask for it to be used instead.
Whichever side of the payment you are on, the same three checks keep the number fair.
Most disputes are really about the income figure or the nights count, not the formula. Settle those two facts — payslips, P60, the care diary — and the amount follows mechanically.
A family-based arrangement or Direct Pay moves 100p in the pound. Collect & Pay burns 20% + 4% in fees — worth avoiding wherever payments are reliable.
The CMS reviews assessments annually against fresh HMRC data. Private arrangements deserve the same habit — re-run the formula when income, nights or households change.
Child maintenance sits inside the wider single-parent budget — these tools cover the rest of it.
See what your salary actually leaves after tax and NI before committing to an amount.
Take-home pay →Nursery and wraparound costs alongside the maintenance that helps meet them.
Childcare costs →Put maintenance in or out of a full household budget and see what balances.
Budget planner →