Free · 2025 · CMS Formula
Child Maintenance Calculator 2025
Calculate child maintenance payments using the Child Maintenance Service (CMS) formula for 2025. Includes overnight stay reductions, deductions for other children, and the impact of shared care arrangements.
Child Maintenance Calculator
CMS Formula 2025
£
Before tax. CMS uses HMRC income data. Reduces the income used for calculation
Nights the child stays with the paying parent
Weekly Payment
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Monthly (× 52/12)
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Annual Total
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How This Was Calculated
How the CMS formula works
The Child Maintenance Service uses a stepped formula based on the paying parent’s gross weekly income. The rates are applied to income after deducting a proportion for any other children the paying parent supports in their household.
- On income up to £800/week (£41,600/year): 12% (1 child), 16% (2), 19% (3+)
- On income from £800–£3,000/week: 9% (1 child), 12% (2), 15% (3+)
- Income above £3,000/week is disregarded in the basic calculation (but can be challenged by court)
- Minimum payment: £7/week if income is between £100–£200/week; £0 below £100/week
Overnight Stay Reductions
52–103 nights: deduct 1/7 · 104–155 nights: deduct 2/7 · 156–174 nights: deduct 3/7 · 175+ nights (shared care): payment halved, then subtract a further £7/week per child. Shared care arrangements can significantly reduce payments where the child spends substantial time with the paying parent.
Frequently asked questions
Does the CMS use gross or net income?
The CMS uses gross income — your income before tax and National Insurance. They obtain this directly from HMRC records rather than from you, which means they use the most recent tax year’s figures unless your income has changed significantly (by 25% or more). You can request a recalculation if your income has changed materially. Pension contributions, Gift Aid donations and certain business expenses are deducted before the calculation.
Is this calculator the same as the official CMS calculation?
This calculator closely follows the published CMS formula and is designed to give an accurate estimate. However, the official CMS calculation may differ in specific circumstances — for example where the paying parent has pension income, rental income, or other sources that the CMS includes in their assessment. For definitive figures, use the government’s official child maintenance calculator at gov.uk or contact the Child Maintenance Service directly. This calculator is for indicative purposes only.
Can maintenance be agreed privately without using CMS?
Yes — parents can agree a private family-based arrangement without involving the CMS at all. This is often faster, cheaper and less adversarial. It’s recommended to put any agreement in writing, even informally. If circumstances change or payments stop, either parent can then apply to the CMS. A court consent order is not required for child maintenance in England and Wales, though it may be obtained as part of wider financial proceedings on divorce or separation.
