Child Maintenance Calculator: How Much CSA Should I Pay or Receive?

Part of: Child Maintenance Lawyer

A child maintenance calculator, still called a CSA calculator by most parents, answers the question how much CSA should I pay from four figures and nothing else: the paying parent’s gross weekly income, the number of children, any other children in that parent’s home, and the nights a year the children stay overnight. The first thing to know is that the CSA no longer sets any of it. The Child Support Agency stopped taking applications years ago, and the Child Maintenance Service (CMS) has handled every new case since 25 November 2013, using a fixed statutory formula (Child Support Act 1991, Sch. 1).

The tool below returns that figure. Then it shows the part no calculator can: whether your family is one the formula does not describe. Our child maintenance specialists regularly advise and assist parents whose figure rests on the wrong income or the wrong nights. Either mistake can sit in the figure for a year unless someone challenges it. This guide covers the law of England and Wales.

Child maintenance calculator: work out what the CMS would set

Parents also look for this as a child support calculator. Whatever the name, you calculate child maintenance from the same four figures. Enter the paying parent’s gross weekly income, the children covered, other children in that household and the overnight stays. The tool applies the statutory rates and shows the weekly, monthly and annual figure. It also shows what Collect and Pay would do to it, and what the figure leaves unanswered.

Do you still pay the CSA, or the CMS?

You now pay the CMS. The Child Maintenance Service opened in stages, first to parents with four or more children on 10 December 2012, then to parents with two or more on 29 July 2013, and then to everyone on 25 November 2013. GOV.UK then records that "in June 2014 we started telling CSA clients that their CSA case will close", and that every CSA arrangement with an ongoing liability had closed by December 2018. Because the name stuck, thousands of parents still search for CSA payments every month, and the old rules they remember no longer apply.

That matters for your money. The old scheme worked from net income, so friends and forum posts that quote net figures will mislead you. The current scheme starts from gross income: the income HMRC charged to tax for the latest available tax year, before Income Tax and National Insurance but after pension contributions (Child Support Maintenance Calculation Regulations 2012, reg. 36). It is not take-home pay, which is why a CMS figure so often looks higher than a paying parent expects. If you are working from an old letter or an old rule of thumb, your figure will be wrong before you begin.

How much CSA should I pay?

Your rate depends on one number: gross weekly income. The CMS sorts every paying parent into one of five bands, then applies a set percentage. Nothing about your relationship, your conduct or who ended it changes the band. So when parents ask how much is CSA payment in real money each week, the honest answer is that the band decides it.

Those percentages come straight from the statute and the reduced-rate figures from the 2012 regulations, so no caseworker can move them (Sch. 1, paras 2 to 5). What a caseworker can get wrong is the income that goes into them, and that is where most disputes start.

How the CMS works out your figure

This is how child maintenance is calculated by the Child Maintenance Service: six steps, always in the same order. The child maintenance calculator above runs exactly this sequence, and so does the CMS calculator on GOV.UK. Knowing the order tells you where your own case can go wrong.

1. Find the income. The CMS asks HMRC for the paying parent's gross yearly income for the latest available tax year.
2. Adjust it. Pension contributions come off. If other children live with the paying parent, gross income drops again, by 11% for one, 14% for two and 16% for three or more. Then it becomes a weekly figure.
3. Pick the band. That weekly figure lands in one of the five bands above.
4. Count the children. The CMS counts the children named in the application, plus any other children the paying parent already supports.
5. Work out the weekly amount. The percentage goes on, and a weekly figure comes out.
6. Take off shared care. Overnight stays reduce the figure, sometimes sharply (GOV.UK step-by-step guide).

Step two only counts other children for whom the paying parent or their partner receives child benefit, and on the reduced rate that adjustment is built into the percentage table instead, which is why a calculator that applies the 11% twice returns a figure that is too low.

Because step one uses last year's tax figures, a promotion, a redundancy or a move into self-employment may not show up for months. The CMS will only use a different figure if current income is at least 25% higher or lower than the HMRC figure, and someone has to ask (reg. 34(2)). That 25% threshold is the single most useful number for anyone whose earnings have just fallen.

How many nights change the child maintenance you pay?

Shared care is the single biggest lever in the formula, and it counts in overnight stays across a year. Day contact, however long, counts for nothing.

• 52 to 103 nights. The amount falls by one seventh.
• 104 to 155 nights. It falls by two sevenths.
• 156 to 174 nights. It falls by three sevenths.
• 175 nights or more. It halves, and another £7 a week comes off for each child.

Nothing happens below 52 nights, and between the steps an extra night is worth nothing at all. However the arithmetic falls, the paying parent cannot be taken below £7 a week (Sch. 1, para. 7). Where more than one child is involved the fractions are added and divided by the number of children, so children on different patterns produce a blended reduction.

The nights are not counted backwards from a diary. The CMS decides how many nights it expects over the 12 months from the effective date, looking first at any agreement or court order about contact and, only if there is none, at the pattern of the past year (reg. 46). A night counts only where the child stays at the same address as the paying parent, and a child boarding at school or in hospital is treated as being with whoever would otherwise have had them. That is why a contact order and a maintenance figure are the same conversation, why a single night either side of a band boundary can change a year of payments, and why the arrangement written down and the arrangement actually happening need to match.

How much CSA would I get if the other parent pays?

As the receiving parent you get the same formula in reverse, so the sum turns on the other parent's gross income and the nights the children spend with them. Two versions of the same question arrive here: how much CSA should I receive, and how much CSA will I get once the deductions come off? You have no say in the percentage. What you can influence is whether the income behind it is honest and complete.

Three practical points decide what actually reaches your bank account. First, the money is yours to use for the children: it is not taxed, and it does not reduce Universal Credit or other benefits. Second, Collect and Pay skims 4% off what you receive. Third, an assessment is worth nothing until it is paid, and of the 240,000 paying parents due to pay through Collect and Pay in the quarter to March 2026, 57,000 (23%) paid no maintenance at all (DWP statistics, March 2026).

If the paying parent's gross income is above £3,000 a week, the formula simply stops. At that point you can ask a court for a top-up maintenance order on top of the CMS figure, because the court keeps that power where the statutory maximum is reached (Child Support Act 1991, s.8(6)).

What if the parent paying CSA is self-employed?

This is where the formula is weakest, and where advice earns its keep. A director can pay themselves a small salary and take the rest as dividends. A sole trader can run costs through the business. In both cases the HMRC figure the CMS starts from can look nothing like the family's real standard of living.

For a sole trader, gross weekly income is the trading profit charged to tax, after carry-forward trade loss relief (reg. 36(1)(d)). A director paid a small salary and the rest in dividends shows a modest employment figure, and the dividends are not in it. The law has answers, but only if someone asks for them. A variation can bring in income the basic calculation misses (GOV.UK: other income and expenses):

• Unearned income. Rent from property, or interest and dividends, of £2,500 a year or more (reg. 69).
• Notional income from assets. Shares, stocks, gold or money worth more than £31,250.
• Diversion of income. Income routed to a new partner, a company or a pension to keep it out of the sum. Profit deliberately retained in a company the paying parent controls is dealt with here.
• Earnings while on benefits. Gross earnings or a pension of at least £100 a week.

You have to claim each of these, evidence it and argue it. The CMS does not go looking. Two practical points decide these cases: the service works from the latest tax year HMRC can give it, which for a self-employed parent can be well over a year old, so a business that has just had a good year may not show up until the next annual review; and a variation has to be evidenced with accounts, dividend vouchers or a Land Registry entry, not a suspicion. Getting that evidence together before you apply is usually the difference between a variation that is agreed and one that is refused. Our specialists assist and advise on which ground fits your facts and what evidence carries weight.

Direct Pay or Collect and Pay: what collecting child maintenance costs

The calculation and the collection are two separate decisions, and the second one changes what leaves the paying parent's account. Direct Pay costs nothing: the CMS works out the figure and the parents move the money between themselves.

Collect and Pay is charged. The paying parent has a 20% collection fee added on top of the maintenance, and the receiving parent has 4% taken off what is passed on (GOV.UK guidance). On a £60 a week calculation that is £72 out and £57.60 in, a gap of £748.80 a year between the two households on the same assessment. The calculator above shows both figures for whatever you enter, because the choice of route is worth as much as an argument about a night or two.

How much can CSA take from a pay packet?

Parents ask how much does CSA take once payments stop, and the answer is as much as your wages will bear. The CMS can order an employer to take the money at source, and the employer has no choice (Child Support Act 1991, s.31). There is a floor, though: the deduction must leave the employee with at least 60% of net earnings, known as the protected earnings proportion (Child Support (Collection and Enforcement) Regulations 1992, reg. 11(2)).

Arrears change the picture. A deduction order can also reach a bank or building society account, and the CMS charges £50 where it has to take action to deduct maintenance from earnings. Beyond that, enforcement through the courts can affect a credit rating or force the sale of property, and where other recovery has failed, the Secretary of State can ask a court to commit the parent to prison or disqualify them from holding a driving licence (Child Support Act 1991, s.39A).

Does a CSA calculator work in Scotland and Northern Ireland?

In Scotland, yes. In Northern Ireland, no. The Child Support Act 1991 and the 2012 calculation regulations extend to England, Wales and Scotland alike, and the rates, the bands and the shared care fractions are identical across the three.

Northern Ireland runs a separate scheme under the Child Support (Northern Ireland) Order 1991, with its own Child Maintenance Service, so an application there is made separately even though the underlying formula was designed to match. We advise and assist families across England and Wales. Where one parent lives in Northern Ireland and the other in England, Wales or Scotland, the case is dealt with by the service for the place where the parent with care lives, not where the paying parent lives (Child Support (Northern Ireland Reciprocal Arrangements) Regulations 1993, Sch. 1, art. 5(5)).

What does a child maintenance calculator miss?

Plenty, and this surprises almost everyone. The formula is deliberately blunt: it was built to produce a fast, cheap, predictable number for the ordinary case, so real family costs sit outside it unless a court or a variation brings them in.

A calculator hands you a number and stops. It cannot tell you whether the income behind that number is the real one, whether the night count would survive a disagreement, or whether the costs your family actually carries fall inside the figure or outside it. Those three questions decide what you pay or receive for the next year, and none of them has a box on the form.

• School fees. Private school fees are not part of the calculation. A paying parent can only ask for the boarding element as a special expense, and school fees themselves usually need a separate court order.
• Travel for contact. You can claim the cost of keeping in regular contact as a special expense, but only where it is more than £10 a week and only if you ask. Ordinary childcare and school uniform are not on the list at all.
• Disability and extra needs. Supporting a child with a disability or long-term illness who lives with you can reduce the figure, again only on request. A court can separately order payments for a disabled child's expenses under s.8(8), and support for a disabled child over 18 has to come from a different route altogether.
• Debts from the relationship. Certain debts, and mortgage or insurance payments on the home you used to share, can count as special expenses.
• Who the child lives with day to day. Only overnight stays register. The school run, the holidays and the sick days do not.
• An income that does not match the life. A director on a small salary taking dividends, or a sole trader running costs through the business, can produce a calculator figure that bears no relation to how the household actually lives. Bringing the rest in takes a variation, and income moved into shares or a company has to be evidenced and argued, not simply asserted.
• A night count the two of you do not agree on. The calculator takes the nights it is told. Where the accounts differ, the CMS decides which arrangement to treat as real, and a single night either side of a band boundary is worth a year of payments.
• When the payments stop. A calculator assumes the liability continues. In fact a child qualifies while they are under 16, or under 20 and in approved education or training, which is why when CSA payments stop catches parents out more often than the rate ever does.
• Everything above the ceiling. Past £3,000 gross a week the calculator simply stops counting, so a top-up maintenance order from a court is the only route to anything beyond it.

A paying parent whose gross income falls under £7 a week, or who lives on benefits, cannot claim special expenses at all. Everything here is a judgement call about which ground to run and what it is worth, which is exactly the point at which a conversation with a specialist changes the outcome.

Before you agree how much CSA to pay: are you on track?

Choose the side you are on, then work down the four numbers any maintenance calculator needs, plus the two that only apply to your side. It takes a minute, and it shows you the gaps before anyone fixes a figure.

What goes wrong when you pay or claim CSA?

The same handful of mistakes come up again and again. Each one is cheaper to avoid than to unpick.

• Using a net figure. The old scheme used net income and the current one does not, so an old rule of thumb produces a wrong answer every time.
• Guessing the nights. If you cannot show the overnight count, you can lose the reduction. Keep a simple record from the start.
• Accepting the HMRC figure without looking. Bonuses, rent and dividends can sit outside it until somebody asks.
• Ignoring the ceiling. Where income runs past £3,000 a week, staying inside the statutory scheme alone can leave money on the table.
• Signing a private deal you cannot enforce. A family arrangement is not binding, and either of you can apply to the CMS instead.
• Missing the challenge window. A figure built on the wrong income, the wrong nights or the wrong number of children is not one you have to live with. Ask the CMS for a mandatory reconsideration first, then take it to the child maintenance tribunal if you still disagree.

Whether a court order or the statutory scheme suits you better is a real choice with consequences, and our guide to the CMS compared with a court order sets out the trade-offs. Once an order is in place you may also need to know how to change the amount later.

How do our specialists assist and advise on child maintenance?

Our specialists start with the number in front of you and work backwards. They explain which band applies and why, and they test whether the income used reflects reality. Where a variation is worth running, they set out the ground, the evidence it needs and the realistic effect on the weekly figure. If the statutory scheme cannot reach far enough, they explain the court routes that can, including Schedule 1 of the Children Act 1989 for unmarried parents and top-up orders for high earners. When enforcement is the problem, they talk you through the options open to you.

What a free child maintenance consultation covers

A free initial consultation is a conversation with a specialist, who gives you initial advice on your circumstances. It does not include drafting or reviewing documents. Before the call, have a rough idea of the other parent's income and how many nights the children stay. It also helps to know what has already been decided between you. Bring the figure the child maintenance calculator gave you, and the conversation starts from something real.

Frequently asked questions: How much CSA should I pay

General information about the law in England and Wales, not advice on your circumstances.

Expert Tip: How much CSA should I pay

Run the calculator twice. Once with the nights you actually have, and once with the nights in whatever order or agreement is on paper. Where those two numbers differ, you are looking at the gap the Child Maintenance Service will decide against you, because it starts with the document and only falls back on the pattern when there is no document. Parents lose a band that way without ever having a row about contact. If the order says alternate weekends and you have the children half the school holidays as well, get the paperwork to say so before the next annual review, not after it.

Garry Steedman, Family Law Consultant (Divorce, Children & TOLATA)