Child Maintenance Calculator
Estimate statutory payments under CMS guidelines using paying parent income, number of children, and overnight shared care nights.
Calculate statutory UK child maintenance payments using official CMS formulas, income bands, and overnight shared care deductions.
See also: CMS Calculator (Child Maintenance Service), NHS Take-Home Pay Calculator, VAT Calculator (UK)
How it is calculated
Basic Band: 1 child = 12%, 2 children = 16%, 3+ children = 19% of gross weekly income; Deductions: 1/7th per 52 nights shared care
Worked example: Parent Earning £600 Gross Weekly with 1 Child and Alternate Weekend Stays
£600 gross weekly income, 1 qualifying child, 52 to 103 overnight stays per year (1 night per week average).
- Check CMS income band: £600/wk falls into the Basic Rate band (£200 to £800/wk).
- Apply 1-child Basic Rate percentage: £600 × 12% = £72.00 per week base maintenance.
- Calculate shared care deduction for 52–103 nights (1/7th reduction): £72.00 ÷ 7 = £10.29 deduction.
- Subtract reduction: £72.00 − £10.29 = £61.71 per week.
- Convert to monthly payment: (£61.71 × 52 weeks) ÷ 12 months = £267.41 per month.
Weekly payment of £61.71 (£267.41 per month).
How to Use This Calculator (Step-by-Step)
- Enter the paying parent’s gross weekly earnings before tax and National Insurance.
- Deduct any employee contributions paid into a registered workplace pension scheme.
- Select the number of qualifying children the maintenance order covers.
- Indicate if the paying parent supports any other children living in their household.
- Choose the average number of nights per year the children stay overnight with the paying parent.
Frequently asked questions
Is child maintenance legally required in the UK?
Parents are legally obligated to financially support their children. Parents can agree to a private family arrangement or request statutory collection via the Child Maintenance Service (CMS).
What is the maximum income cap for CMS?
The CMS caps gross weekly earnings at £3,000 (£156,000 per year). If the paying parent earns more, the receiving parent can apply to court for a "top-up" order under the Children Act 1989.
Should I enter gross pay or take-home pay?
Gross weekly income. Since the 2012 CMS rules update, child maintenance is calculated from gross taxable income reported to HMRC, not net take-home pay, and the input helper specifies before tax and National Insurance, after workplace pension contributions.
How do other children in my household affect the amount?
Supporting other children living in the paying parent household reduces the assessable income: 11% for one other child, 14% for two, and 16% for three or more, as set out in the input options.
How do overnight stays change the payment?
Shared care reduces the base amount in bands: 52 to 103 nights a year gives a one-seventh reduction, 104 to 155 nights two-sevenths, and 156 to 174 nights three-sevenths, while fewer than 52 nights gives no reduction.
What happens with equal shared care of 175 nights or more?
The input option for 175 or more nights describes equal shared care, which halves the base amount and then adds 7 pounds per child per week. Select that band when care is genuinely shared equally.