Child Maintenance for 1 Child: Real Costs and Calculations (2026)

The first time a maintenance payment landed in my account, I remember opening my banking app almost nervously, like the number itself would tell me something about whether this was all going to be okay. It wasn’t a huge sum. It wasn’t nothing either. Mostly, it just sat there next to the nursery invoice and the weekly shop, and I remember thinking: is this actually meant to cover everything, or just… something?

If you’re in that exact spot right now — one child, one maintenance figure, trying to work out whether it’s fair, whether it’s enough, whether you’re even looking at it correctly — let’s actually walk through the real mechanics, not just the headline percentage everyone quotes.

When Calculating Maintenance for a Minor Child, What Actually Counts?

A “qualifying child” for CMS purposes is generally any child under 16, or under 20 if they remain in full-time, non-advanced approved education (A-levels, T-levels, and similar — university doesn’t count here). The calculation itself considers:

• The paying parent’s gross weekly income (before tax)
• Any pension contributions, which reduce the assessable income
• Whether the paying parent supports other children in their household
• The number of qualifying children the maintenance calculation covers
• Overnight shared care nights between the two homes

For one child specifically, the number of qualifying children input is simply “1,” which places you at the lower end of each percentage band compared to families with two or three children being assessed.

The Actual Formula for One Child

Most working parents fall into the Basic Rate band (gross weekly income £200–£800), where the calculation for one child is:

Gross weekly income × 12% = weekly maintenance, before any shared care adjustment.

If income exceeds £800/week, the Basic Plus Rate applies a lower 9% to the portion above £800, while the first £800 is still calculated at the standard rate.

What This Looks Like at Real Income Levels

Here’s the maths worked through properly, one child, Basic Rate, no shared care adjustment:

Gross Annual Income	Weekly Maintenance (approx.)	Monthly (approx.)
£18,000	~£42	~£180
£24,000	~£55	~£240
£30,000	~£69	~£300
£35,000	~£81	~£350
£41,600	~£96	~£416

Now factor in shared care. If the child stays with the paying parent one night a week or more (52+ nights/year), that figure drops by a further seventh. At 175+ nights a year, roughly equal care, it drops by half.

Worth sitting with that for a second, because it’s the part that catches a lot of receiving parents off guard: the same child, the same income, produces a genuinely different monthly figure depending purely on how the overnight nights fall. That’s not unfair by design — it reflects that the paying parent is also directly covering costs during those nights — but it does mean the headline “12% of income” figure is rarely the actual number that lands in anyone’s account.

What Is the Biggest Factor in Calculating Child Support?

Income, decisively. Everything else — shared care, other children, pension contributions — adjusts the outcome, but gross weekly income sets the scale the whole calculation is built on. A parent earning £20,000 and a parent earning £40,000 will produce roughly double the maintenance figure for the same single child, all else being equal.

So What Does One Child Actually Cost?

This is the part no CMS calculator will tell you, because it’s not what the formula is designed to measure. The CMS figure isn’t calculated based on what a child in your specific area actually costs to raise — it’s calculated purely from the paying parent’s income. That means the maintenance figure and the real cost of raising a child can, and often do, sit quite far apart.

Broadly, the categories that tend to eat into a maintenance payment fastest:

• Food and everyday essentials — the steady, unavoidable baseline
• Clothing, especially during growth spurts, which arrive with zero warning and zero budget flexibility
• Childcare or after-school care, if you’re working — and this is a big one, since it’s not automatically covered by standard maintenance
• School-related costs — uniforms, trips, equipment — again, generally outside the standard figure
• Activities and hobbies, which add up faster than they seem to individually

This is exactly why maintenance and “full cost of raising a child” are two different numbers, and treating them as interchangeable is where a lot of resentment quietly builds between separated parents.

If the Maintenance Figure Doesn’t Cover Everything, What Then?

A few realistic paths, depending on how things stand between you and the other parent:

• A separate agreement for specific extra costs — school trips, childcare, uniforms — split by mutual agreement rather than folded into the standard maintenance figure.
• Mediation, if you can’t agree on how to split those extras and keep having the same argument every term.
• Reviewing the CMS calculation itself, if you believe the paying parent’s declared income doesn’t reflect reality (self-employment income and cash-in-hand work are common sources of dispute here) — you can request a mandatory reconsideration.
• A court application, in specific circumstances like genuinely equal shared care (where CMS may have no jurisdiction at all) or income above the CMS ceiling of £3,000/week.

How Much Maintenance Does a Husband Have to Pay?

Worth separating clearly from child maintenance: if this is about spousal maintenance rather than child support, the UK has no fixed formula for it. Courts weigh a range of factors under the Matrimonial Causes Act 1973 — income, needs, the length of the marriage, standard of living during it, and contributions made by each party, including non-financial ones like childcare. It’s typically negotiated between parties or decided case-by-case by a court, not calculated from a percentage the way child maintenance is.

Common Mistakes to Avoid

• Assuming the CMS figure is meant to represent the full cost of raising your child. It’s calculated from income, not from actual living costs in your area.
• Not accounting for shared care nights when estimating what to expect. The same income can produce a noticeably different figure depending on overnight stays.
• Assuming childcare, school trips, or uniforms are automatically included. They generally need separate agreement.
• Letting frustration over “the number feeling too low” turn into conflict, rather than checking whether the income figure being used is actually accurate — that’s often where the real gap lies.
• Confusing child maintenance with spousal maintenance. They’re calculated on completely different bases.

Final Thoughts

That first payment landing in my account didn’t answer the question I actually had, which wasn’t “is this the right number” — it was “am I going to be okay.” Those are genuinely different questions, and no formula, however precisely calculated, answers the second one. What the formula does give you is a starting point you can actually understand and check, rather than a mystery figure to just quietly resent. That’s worth something, even on the months when it still doesn’t quite stretch far enough.

FAQ

When calculating maintenance for a minor child, what counts?
A qualifying child is generally under 16, or under 20 if in full-time non-advanced approved education; the calculation uses the paying parent’s gross income, shared care nights, and any other children they support.

What is the biggest factor in calculating child support?
The paying parent’s gross weekly income — it sets the scale for the entire calculation, before any other adjustment is applied.

How much maintenance does a husband have to pay?
If referring to spousal maintenance, there’s no fixed UK formula — courts consider income, needs, marriage length, and standard of living under the Matrimonial Causes Act 1973 instead of a set percentage.