Child Maintenance Calculator (2026 Statutory CMS Formula)
Calculate statutory child maintenance in England, Wales, and Scotland using the official 2026 Child Maintenance Service gross income formula, pension adjustments, household reductions, and overnight stay deduction bands.
The Child Maintenance Service calculates liability based on the paying parent’s gross weekly income before income tax and National Insurance (sourced automatically from HMRC), minus deductible pension contributions. Reductions are then applied for other children living in the household, followed by overnight care shared with the paying parent.
Estimated Statutory Child Maintenance Liability
Equivalent to £241.43 per calendar month (£2,897.14 per year).
Understanding Your Calculation & Next Steps
Under the Child Support Act 1991, statutory child maintenance applies where the child is under 16, or under 20 and in full-time non-advanced education. Key factors that alter this baseline assessment include:
Income Diversion Variations
If the paying parent retains substantial business profits in a limited company or takes loans/dividends to artificially reduce gross PAYE, you can apply for a Regulation 57 Variation for unearned income.
Special Expenses Relief
If the paying parent incurs more than £10/week in travel costs to maintain contact with the child, this can be deducted from gross income before calculating liability.
Equal Shared Care (50/50)
Where day-to-day care is genuinely shared equally (175+ nights/year) and both parents provide equal care, the statutory liability drops by 50% plus an additional £7/week per child.
If the CMS has used incorrect income figures or ignored proven overnight care, you have a strict 30-day deadline from the date of the decision letter to request a Mandatory Reconsideration. If the decision is upheld, you can appeal to the independent First-tier Tribunal (Social Entitlement Chamber) on Form SSCS2.
Read our Step-by-Step CMS Mandatory Reconsideration & Tribunal Guide →
Is your child maintenance question part of a family court case? EvidenceCanvas is an online tool for people who represent themselves in the family court. It can help you put dates, messages and documents into a chronology and a draft statement for the family court. It does not deal with Child Maintenance Service assessments, mandatory reconsiderations or tribunal appeals.
It is a paid tool with monthly plans and one-off options, and a limited free plan to try it. Check the current prices on its website before you choose a plan. It is not a law firm, it does not give legal advice and it cannot tell you how your case will turn out. If you can get legal advice or legal aid, consider that first.
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