- Regulation 50 of the Child Support Maintenance Calculation Regulations 2012 decides who counts as the "paying parent" when both parents share day-to-day care.
- A parent is the paying parent if, and only if, they provide day-to-day care to a lesser extent than the other. If care is genuinely equal, neither parent pays — the CMS's own factsheet confirms it.
- So why are you being assessed? Almost always paragraph (3): the parent receiving Child Benefit is assumed to provide more care — unless there is evidence to the contrary.
- That assumption can be answered with evidence. The evidence that carries weight is the boring kind: records made at the time, day after day, not reconstructed later.
- Close to equal but not exactly? The shared-care bands reduce the amount instead — a different mechanism, covered in our guide to proving 50/50 shared care coming soon.
If it's late and you've just opened a letter that calls you the "non-resident parent" of children who were asleep upstairs when you read it — this page is for you. Take a breath. The rule itself is more reasonable than the letter suggests. The gap between the two is what this guide explains.
What does Regulation 50 actually say?
Regulation 50 sits in the Child Support Maintenance Calculation Regulations 2012, the rulebook the Child Maintenance Service (CMS — the government service that calculates and collects child maintenance) works from. Its heading is "Parent treated as a non-resident parent in shared care cases", and it covers the situation where one parent applies for maintenance but the other parent also provides a home for the child and shares their day-to-day care.
The part that matters is paragraph (2). Slightly tidied for readability, it says the parent named in the application is to be treated as the non-resident parent (the CMS calls this the "paying parent"):
Reg 50(2)"…if, and only if, that person provides day to day care to a lesser extent than the applicant."
read that again — it's the whole question.
If, and only if. Not "if they earn more". Not "if the other parent applied first". Not "if the children's official address is elsewhere". Not "if the other parent works less". Not "if the other parent covers a few more of the school holidays". The regulation turns on one question: who provides day-to-day care to a lesser extent?
And if the honest answer is neither — if care is genuinely equal — then neither parent can be treated as the non-resident parent, and there is no paying parent for the CMS to assess. The Department for Work and Pensions says this plainly in its own factsheet on living arrangements: where the day-to-day care of a child is equal between the two parents, "the paying parent does not have to pay any child maintenance for that child."
So the rule is on the side of equal parents. Which makes the next question the painful one.
Why has the CMS decided I have to pay, then?
Because of paragraph (3) — the Child Benefit assumption. It says that where the applicant receives Child Benefit (the regular government payment made to one person per child) for the child:
Reg 50(3)"…the applicant is assumed, in the absence of evidence to the contrary, to be providing day to day care to a greater extent than any other person."
In plain English: the CMS doesn't start from a blank page and weigh up both households. It starts from a shortcut. Whoever gets the Child Benefit is assumed to be the parent with more care — and the job of showing otherwise lands on you. Child Benefit can only be paid to one person per child, so in a genuinely 50/50 family, one parent holds a card the other simply cannot hold. And it's very often decided by accident: coming out of a relationship or a marriage, one of you happens to be the one who claimed the Child Benefit years ago. You may not even realise it's the case — it's not the kind of thing anyone is thinking about in the middle of a painful break-up.
Notice what the assumption is not, though. It is not a verdict. The regulation's own words — "in the absence of evidence to the contrary" — tell you it's a starting point that evidence can answer. The rule doesn't say the Child Benefit recipient provides more care. It says they're assumed to, until the record says otherwise.
I know how this feels from the inside. My children were with me a little over half the time — around 54% of overnights across more than a year of logged days — and I was still assessed as the paying parent, at roughly £737 a month. Equal-or-better care on paper that didn't exist yet; a four-figure annual difference decided by which name was on the Child Benefit claim. The assessment wasn't malicious and it wasn't personal. It was a default doing what defaults do when nobody hands the decision-maker anything better.
One more detail worth knowing: paragraph (4), added in 2013, closes an apparent loophole. If the Child Benefit recipient has opted out of receiving the payments (some higher earners do, because of the tax charge), they are still treated as receiving Child Benefit for this purpose. The assumption follows the entitlement, not the bank transfer.
What does "equal day-to-day care" actually mean?
Here's where it gets more interesting than people expect. Regulation 50 says "day to day care" — it does not say "nights", and it does not say "school holidays".
Both matter, of course. The CMS's shared-care bands (more on those below) are built entirely on overnight stays, so overnights are the number everyone learns to count. But day-to-day care is a wider idea than where a child sleeps: the school runs, the meals, the GP appointments, the long Saturday afternoons, the uniform washed and the reading record signed, the Sunday-night care managing the build-up to school on a Monday morning. Two parents can have identical overnight counts and quite different shares of the actual caring day.
That's why, when I started keeping my own record, I ended up measuring two different things and keeping them separate:
A simple yes/no per night: who did the children sleep with? Over the first full year of the record, 197 nights of 365 were with me.
The fuller picture: across the whole day, how many hours was I actually the parent doing the caring?
A detail worth understanding, because a decision-maker will ask it too: those care-hours percentages are shares of the cared-for hours, not of the whole calendar. Across that year, about 86% of all elapsed hours were logged as care by one parent or the other. The remaining 14% is mostly school time — the hours when the children were in the classroom, attributable to neither parent. A care record that honestly excludes school hours (and splits any genuinely shared time evenly) is more credible than one that quietly books the school day to whoever did the drop-off. The gap in the total isn't a flaw in the record; it's the record telling the truth.
Two measures, two different numbers, both pointing the same way. And that's precisely why it's worth keeping both: they are independent pieces of evidence, and two independent measures agreeing is more persuasive than one number standing alone. (If one had said 54% and the other 45%, I'd have wanted to know that too — an honest record is only useful because it would tell you either way.)
This is also why equal care is harder to evidence than people expect. "We do 50/50" feels like a fact when you live it. But day-to-day care is hundreds of small, undocumented acts, and by the time anyone asks you to prove it, most of them have evaporated. A pattern that took a year to happen takes a year to record — which is the strongest argument for starting the record before you need it. We'll look at how one 2025 court case treated the precision of exactly this kind of record in our plain-English guide to OS v DT coming soon.
How do I rebut the Child Benefit assumption?
The regulation asks for one thing: "evidence to the contrary". It deliberately doesn't give a shopping list — so here are the categories that, in my experience of building a Regulation 50 bundle and in the CMS's own published guidance (which mentions accepting "formal, informal or spoken evidence" of care arrangements as well as court orders), tend to do the work:
Court orders and formal agreements. If a child arrangements order sets out the pattern of care, that's the clearest independent statement of what was supposed to happen. It doesn't prove what actually happened, but it frames everything else.
Independent third-party records. School registers and communications, GP and dentist records, clubs and childcare invoices — documents created by people with no stake in your dispute, showing who was where. These carry weight precisely because you didn't write them.
A contemporaneous care diary. "Contemporaneous" is the lawyer's word for written down at the time, not reconstructed later. A record kept nightly — one line a day, dated, dull — reads completely differently from a spreadsheet assembled the weekend before a deadline. When I eventually made my case, the core of it was 447 days of logged data: not dramatic, not argumentative, just day after day of what actually happened.
Supporting material. Receipts, photos with timestamps, ordinary messages about handovers and pickups. Individually small; together, texture.
And one principle over all of it, which I'd hold to even if it weren't also the practical advice: the record has to be true. A diary only has value because it's honest — which means logging the nights that didn't go your way with exactly the same one line as the nights that did. A record that only remembers your good weeks isn't evidence, and decision-makers have seen a thousand of them. The only record worth keeping is the one you'd be comfortable with anyone checking.
What if we're close to equal, but not exactly?
Then Regulation 50's all-or-nothing question is answered — one of you does provide care to a lesser extent — and the calculation moves to a different mechanism: the shared-care bands. These reduce the weekly maintenance amount based on how many nights a year the child stays overnight with the paying parent (GOV.UK sets them out):
| Nights per year with the paying parent | Reduction per child |
|---|---|
| 52–103 | 1/7 (about 14%) |
| 104–155 | 2/7 (about 29%) |
| 156–174 | 3/7 (about 43%) |
| 175 or more | 1/2, plus an extra £7 a week |
Two things to note. First, the bands run on overnights only — the wider day-to-day care picture that matters for Regulation 50 doesn't move you between bands. Second, the difference between 174 and 175 nights, or between "equal" and "nearly equal", is real money — which is why the counting itself becomes the argument. If the other parent has told the CMS a different number of nights than you have, the evidence question takes centre stage, and that deserves its own guide: How to prove 50/50 shared care to the CMS coming soon.
Frequently asked questions
We genuinely do 50/50 — why am I still paying child maintenance?
Almost certainly because of the Child Benefit assumption in Regulation 50(3): the parent receiving Child Benefit is assumed to provide more day-to-day care unless there is evidence to the contrary. Until that evidence is in front of a decision-maker, the default stands. The assumption is rebuttable — the regulation's own wording invites evidence — but the practical burden of producing it sits with the parent who doesn't get the Child Benefit.
The other parent opted out of actually receiving Child Benefit payments. Does the assumption still apply?
Under Regulation 50(4), yes. A person who has elected not to receive Child Benefit payments (often because of the High Income Child Benefit Charge) is still treated as receiving it for the purposes of the assumption. It follows the claim, not the payments.
Is "equal care" measured in nights or in time?
Regulation 50 says "day to day care", which is broader than overnights — it's the whole picture of who does the caring. The shared-care bands, by contrast, are counted purely in overnight stays. They're two different measures, which is why it's worth recording both your overnights and your care hours, separately.
Why don't care-hours percentages add up across the whole day?
Because part of every school day belongs to neither parent. In a truthful record, the hours a child spends at school aren't claimed by anyone — in a typical year that's roughly 14% of all hours. Care-hours shares are calculated over the time a parent was actually providing care, with genuinely shared time split evenly. A record that shows this gap is being honest, not incomplete.
What evidence do I need to show equal day-to-day care?
The regulation doesn't prescribe a list — it simply says "evidence to the contrary". In practice that means court orders or agreements, independent records (school, GP, clubs), a care diary kept at the time rather than reconstructed later, and supporting material like receipts and messages. Contemporaneous and boring beats dramatic and remembered. Every case turns on its own facts, so for advice on yours, speak to a solicitor or a specialist service.
If care really is equal, does either parent pay anything?
For that child, no — the DWP's own factsheet states that where day-to-day care is equal between the two parents, the paying parent does not have to pay any child maintenance for that child. Parents can still choose to share costs between themselves however suits their family.
Sources
- Regulation 50, The Child Support Maintenance Calculation Regulations 2012 (SI 2012/2677) — legislation.gov.uk (latest revised version; verified August 2026)
- How the Child Maintenance Service works out child maintenance — GOV.UK (shared-care bands and rates)
- How your child's living arrangements affect child maintenance — DWP factsheet, GOV.UK (last updated 27 October 2023)
You've just read the rule. The other half is the record — the quiet, one-line-a-day kind that was being kept long before anyone asked for it. That's what Evincio is for.