How is child maintenance calculated?

Child maintenance is money the parent who does not provide the main day-to-day care (the 'paying parent') puts towards their children's living costs. You can agree it privately as a 'family-based arrangement', or use the Child Maintenance Service (CMS), which works out the amount and can collect it.

The CMS calculates from the paying parent's gross weekly income — before tax and National Insurance, but after pension contributions — taken from HMRC figures. On the basic 'standard rate', for gross weekly income between £200 and £800, the payer gives 12% for one child, 16% for two children, and 19% for three or more. A 'reduced rate' applies between £100 and £200 a week, and income above £800 a week is charged a smaller percentage on the slice above that level.

The figure is then cut for shared care: the more nights a year the children stay overnight with the paying parent, the bigger the reduction — from one-seventh off at 52 nights up to a half off at 175+ nights, with usually no maintenance due for genuinely equal shared care. Other children the paying parent supports also reduce the amount.

Asking the CMS to collect the money ('Collect & Pay') adds fees — a 20% surcharge for the paying parent and a 4% deduction from the receiving parent — so a private arrangement or 'Direct Pay' is usually cheaper. There is a one-off £20 fee to open a CMS case, waived for under-19s and survivors of domestic abuse.