How child maintenance works after divorce in the UK

In the UK, child maintenance is calculated under the Child Maintenance Service formula: 12% of the paying parent's gross weekly income for one child, 16% for two children, and 19% for three or more. Income above £156,000 a year (gross) is not counted. The figure is reduced by one seventh for each overnight the paying parent has the child each week, so a 50/50 overnight split materially reduces the payment. Most separated parents in the UK do not use the Child Maintenance Service directly; they agree the figure between themselves (a "family-based arrangement") using the CMS calculation as a reference point. The CMS becomes involved when one parent will not pay, when the calculation is disputed, or when the relationship is too high-conflict for direct contact. Child maintenance is recalculated when either parent's circumstances materially change: a new job, redundancy, an additional child, a change in the overnight split.

The first time I saw the number on paper I felt slightly winded by it. Not because it was unreasonable. Because it was a number, and the number had my children's names on the calculation and the words "support payments" underneath. It made what had been a marriage feel like a contract for the first time.

We had agreed not to go through the Child Maintenance Service directly. The CMS formula was the reference, but we wanted to settle it between us as a family-based arrangement. The mediator walked us through the calculation. We did 16%, two children, on my gross weekly income, with a reduction of two sevenths because the children are with me two nights a week. That came out to a monthly figure that was a real chunk of my take-home pay.

The first conversation about it in mediation was not really about the formula. It was about everything the formula did not capture. School trips. School uniform. The two-week summer holiday when I would have them and would be feeding them and would also be paying their mother. The football boots that get outgrown every three months. The Christmas-and-birthday question. The formula does not have a column for any of that, and I had assumed it would.

What we agreed in the end was the CMS-formula figure paid monthly by standing order, plus a separate joint account for the "shared costs": uniform, school trips, club fees, birthday and Christmas presents. We both pay in a fixed amount each month. Whichever of us spends from it does the spending; the other does not get to second-guess it. The shared-costs account was the thing that finally made the formula feel less like rent on my own children.

In a Solo Session with Meedi about three weeks into the new arrangement, I told her I was struggling with the resentment. The number itself was fine. The fact that the children's mother and I were now financially entangled through a standing order, possibly for the next ten years, was harder. Meedi asked me whether the resentment was about the money, or about the change in the relationship that the money represented. The honest answer was the second one. The money was just the receipt.

Once I could name that, the standing order stopped feeling like a wound and started feeling like a logistical decision I had made on a particular Tuesday. It is still occasionally a wound. The frequency is lower.

A few practical things that took me too long to learn:

The figure changes when your income changes. If you take a pay cut, the calculation goes down. If you get a promotion, it goes up. The recalculation does not happen automatically; one of you has to flag the change and re-run the numbers. The arrangement we set up has an annual check-in every January, plus an "either of us can request a recalculation if something material changes" clause. Most separated couples skip this and end up with a figure that is years out of date.

The number is calculated on gross income, not net. This caught me out the first time we ran it. Self-employment income gets calculated on the net profit figure from your tax return, not turnover.

Overnight stays matter mathematically. If you go from one night a week to two, the maintenance figure drops by one seventh. This is not a reason to fight over the schedule. It is a reason to know the maths when the schedule is being decided, because the financial and parental questions are connected even though we try to keep them separate.

Mediation is not the cheapest path to settling this if everything goes smoothly between you, but it is the cheapest path to settling it if there is any friction at all. Family mediation costs considerably less than going through the CMS dispute process or, worse, court. The CMS itself charges fees once they are involved (a £20 application fee, plus 20% added to payments for "collect and pay" service if they manage the standing order between you). Most people only learn about those fees after they have already opted in.

If you and your ex can talk about money without it turning into a fight, a family-based arrangement is the cleaner path. If you cannot, do not waste a year trying to make it work. The CMS exists for exactly that situation, and being in CMS is not a failure on either of your parts. It is a system designed to take the weekly transaction out of the relationship so the relationship can do whatever else it needs to do.

The full financial picture sits inside the wider settlement, which is the slower-burning conversation. Maintenance is the part that runs through the household every month; the settlement is the one-off division of the things that took years to build. Both matter. Neither does the other's job.