Child Maintenance Calculator UK 2025 — Estimate Your CMS Payments
The Child Maintenance Service (CMS) calculates payments using a percentage of the paying parent's gross income. Use our free calculator to estimate weekly, monthly and annual payments under current CMS rates, including reductions for shared overnight care arrangements.
Based on CMS basic rate using gross weekly income. Call CMS on 0800 171 2345 for an official calculation. Flat rate (£7/week) applies at income under £100/week. Reduced rate applies at £100–£200/week.
How the Child Maintenance Service Works
The Child Maintenance Service (CMS) is a government body established under the Child Maintenance and Other Payments Act 2008. It replaced the Child Support Agency (CSA). The CMS calculates the amount of child maintenance the paying parent (usually the non-resident parent) should pay to the receiving parent, based on the paying parent's gross annual income from HMRC data.
CMS Income Rates 2025
| Income Level | Rate | Calculation |
|---|---|---|
| Nil rate | Gross income below £7/week or receiving certain benefits | £0 per week |
| Flat rate | Gross income £7–£100 per week | £7 per week |
| Reduced rate | Gross income £100–£200 per week | Sliding scale from £7 upwards |
| Basic rate (1 child) | Gross income above £200/week | 12% of gross weekly income |
| Basic rate (2 children) | Gross income above £200/week | 16% of gross weekly income |
| Basic rate (3+ children) | Gross income above £200/week | 19% of gross weekly income |
Shared Care Reductions
If the child stays overnight with the paying parent, the maintenance amount is reduced to reflect shared costs. The reductions are based on the number of nights per year:
- 52–103 nights/year: 1/7 (approx 14%) reduction
- 104–155 nights/year: 2/7 (approx 29%) reduction
- 156+ nights/year: 3/7 (approx 43%) reduction
Family-Based Arrangements vs CMS
Parents are always encouraged to try a private family-based arrangement first. This can be any amount both parents agree — there is no required minimum. The benefit is avoiding CMS fees and maintaining flexibility. However, private arrangements are not legally enforceable unless made into a consent order. If the arrangement breaks down, either parent can apply to the CMS at any time.
CMS Collection Charges
Applying to the CMS is free. However, if the CMS collects and transfers payments (the Collect and Pay service), fees apply: the paying parent pays an additional 20% on top of maintenance, and the receiving parent has 4% deducted from each payment. The Direct Pay arrangement (where the paying parent pays the receiving parent directly) has no collection charges.
What Counts as Income for CMS Purposes?
The CMS uses HMRC gross annual income data, which includes: employment earnings, self-employment profit, pension income (excluding state pension), rental income, and certain benefits. Dividends are included if the paying parent is a shareholder in their own company. The CMS can conduct an income review if a parent believes the income figure is inaccurate.