CMS Number: How to Contact the Child Maintenance Service and How It Works
Updated: Oct 30
Last updated: 30 October 2026 · Written by the family law paralegal team at Court Help Limited
In short: The CMS number is 0800 171 2345 (Monday to Friday, 8am to 6pm, checked on GOV.UK on 30 October 2026). The Child Maintenance Service is the government service that works out how much a paying parent should contribute towards a child, arranges the payments and can chase them. You only need it if parents can't agree a family-based arrangement between themselves.
Key facts about the Child Maintenance Service
Question | The short answer |
CMS phone number | 0800 171 2345, Monday to Friday, 8am to 6pm (GOV.UK, checked 30 October 2026) |
Welsh language line | 0800 232 1979 |
Relay UK | 18001 then 0800 171 2345 |
Does it cost anything to apply? | No. The £20 application fee was scrapped on 26 February 2024 |
Which children are covered? | Under 16, or under 20 if in approved education or training |
How much is paid? | Worked out from the paying parent's gross income, the number of children and overnight stays |
Fees for Collect and Pay | 20% added for the paying parent, 4% taken off for the receiving parent |
Fees for Direct Pay | None |
First payment | Usually within 12 weeks of applying (GOV.UK) |
Disagree with a decision? | Ask for a mandatory reconsideration within 30 days, then appeal on form SSCS2 |
What is the CMS number and how do I contact the Child Maintenance Service?
The main CMS number for cases in England, Scotland and Wales is 0800 171 2345. GOV.UK lists the lines as open Monday to Friday, 8am to 6pm. If you'd rather speak Welsh, the number is 0800 232 1979. If you can't hear or speak on the phone, you can use Relay UK by dialling 18001 then 0800 171 2345, and there's a British Sign Language video relay service linked from the GOV.UK contact page for the Child Maintenance Service. We checked all of these on 30 October 2026. Numbers and opening hours do change, so please look at that page before you ring.
Northern Ireland has its own number, listed on nidirect. If you already have a case, you can also message the service through your online CMS account, which is often quicker than waiting on the phone. Letters for cases in England, Scotland and Wales go to Child Maintenance Service 21, Mail Handling Site A, Wolverhampton, WV98 2BU. Letters for Northern Ireland cases go to Child Maintenance Service 24 at the same address.
A tip from experience: before you call, have your CMS reference number (or the one the online tool gave you), your National Insurance number and your bank details in front of you. If you're calling about the other parent's income or a change of address, jot down the dates. It saves a second call.
What is the Child Maintenance Service (CMS)?
The Child Maintenance Service (CMS) is the government's statutory child maintenance service. It works out how much child maintenance should be paid, arranges the payments, and can take action if a parent doesn't pay. It can also try to trace a parent whose whereabouts aren't known and help where there's a disagreement about who the child's parent is.
You'll still see the older terms used. The parent who doesn't have main day-to-day care of the child used to be called the non-resident parent (NRP). The CMS now calls them the paying parent. The parent or person with main day-to-day care used to be called the parent or person with care (PWC). The CMS now calls them the receiving parent. Child maintenance is there to help with the child's everyday living costs once the parents live apart.
Both parents are responsible for the costs of bringing up their children, even if one of them doesn't see the child. Getting child maintenance doesn't affect the receiving parent's benefits, including Universal Credit, and it isn't taxed.
How does the CMS work?
The CMS is one option, not the only one. If both parents can agree an amount and how it's paid, you can make a private (family-based) arrangement. It can be a standing order, a bank transfer or anything else that suits you both. The CMS doesn't need to be involved, and you can still ask it to step in later if the arrangement breaks down. If you're not sure what should be covered, our guide on what child maintenance covers, including Christmas and extra costs goes through it.
If you can't agree, either parent can ask the CMS to work out the amount. In practice it goes like this:
You use the GOV.UK "Get help arranging child maintenance" tool, which gives you a reference number.
You apply to the CMS online or by phone, giving that reference number, your bank details and your National Insurance number.
The CMS contacts the other parent and gets the paying parent's income from HM Revenue and Customs (HMRC).
It sends both of you a decision and a payment plan showing how much is due and when.
Payments start. GOV.UK says the first payment is usually made within 12 weeks of applying.
The CMS will share your name and your child's name with the other parent, but not your address. If it isn't safe for the other parent to know where you live, or your new name, tell the CMS when you apply.
How do I apply to the CMS, and is it free?
You start with the "Get help arranging child maintenance" tool on GOV.UK. It lets you compare options, set up a private arrangement or apply to the CMS. If you can't use the tool, you can phone the CMS number above instead.
Applying is free. The £20 application fee was removed on 26 February 2024, so you won't be asked to pay anything to open a case. There's more on that change in our article is it free to apply to the Child Maintenance Service?
To be eligible, you need to live in the UK as your main home and have the right to live here. The child must be under 16, or under 20 if they're in approved education or training. Either parent can apply, even if they don't live with the child, and so can a grandparent with main day-to-day care, a guardian, or (in Scotland only) a child over 12.
There are some situations where you can't use the CMS. You can't apply if the child and the parent with main day-to-day care live outside the UK, and you usually can't apply if the paying parent lives and works abroad, unless they work for certain British organisations such as the Civil Service, the armed forces, the NHS or a UK-registered company. You also can't use the CMS if there's a court-approved consent order dealing with child maintenance that is less than a year old.
How is CMS child maintenance calculated?
The CMS looks at the paying parent's yearly gross income, which it gets from HMRC. That covers earnings from employment or self-employment, and pensions. Student loans and grants don't count. The yearly figure is turned into a weekly one, and the CMS then checks for things that change it, such as pension contributions or other children the paying parent supports. Older versions of this article said the CMS always uses the last complete tax year. GOV.UK now simply says the CMS uses income information supplied by HMRC, so don't rely on an old year's figure. If the paying parent's income changes by 25% or more, either parent can report it and the amount can be looked at again. Either parent can ask for extra income, assets or certain expenses to be taken into account.
The weekly income then decides which rate applies:
Paying parent's gross weekly income | Rate and what it means |
Below £7 | Nil rate: nothing to pay |
£7 to £100, or on certain benefits | Flat rate: £7 a week |
£100.01 to £199.99 | Reduced rate: set by a formula |
£200 to £3,000 | Basic rate: 12% for 1 child, 16% for 2, 19% for 3 or more on the first £800; then 9%, 12% or 15% on income above £800 |
Income not known | Default rate: £38 (1 child), £51 (2 children), £64 (3 or more) a week |
The basic rate percentages come from Schedule 1 to the Child Support Act 1991. If the paying parent has other children living with them, their income is reduced first (by 11% for one child, 14% for two and 16% for three or more) before the percentage is applied. Income above £3,000 a week isn't counted, but the receiving parent can ask the court for extra maintenance. Our guide to Schedule 1 of the Children Act 1989 explains that court route.
Here's a simple worked example. A paying parent earns £500 a week before tax, has one child to pay for and no other children, and the child doesn't stay overnight. The basic rate is 12% of £500, which is £60 a week. The real figure can differ once pension contributions, other children or shared care are factored in, so use the GOV.UK calculator for an estimate.
Who doesn't have to pay? GOV.UK says a parent with no income who is a full-time student or in prison doesn't have to pay. A parent on benefits usually pays the flat rate of £7 a week rather than nothing, so being out of work doesn't automatically mean a nil assessment.
How do overnight stays (shared care) change the amount?
Overnight stays matter. If the child stays overnight with the paying parent on average at least 52 nights a year, the amount goes down. This applies to the reduced and basic rates:
Overnight stays a year | Reduction |
52 to 103 | 14.29% (one seventh) |
104 to 155 | 28.57% (two sevenths) |
156 to 174 | 42.86% (three sevenths) |
175 or more | 50%, plus a further £7 a week |
In the example above, if the child stayed 60 nights a year with the paying parent, the £60 would come down by one seventh to about £51.43 a week. Maintenance can't drop below £7 a week. If you agree the child stays at least 52 nights but can't agree the exact number, the CMS assumes 52. Where the paying parent gets benefits and pays the flat rate, 52 or more nights means nothing is payable for that child. Our guide to shared care arrangements and what they mean covers the court side of shared care.
How is CMS maintenance paid: Direct Pay or Collect and Pay?
There are two ways of paying through the CMS.
Direct Pay. The CMS works out the amount and the payment schedule, and the paying parent pays the receiving parent directly, for example by standing order. There are no collection fees.
Collect and Pay. The CMS collects the money from the paying parent and passes it on. Payments can be taken straight from the paying parent's earnings, bank account, benefits or pension. If Direct Pay payments are missed, report it to the CMS, which can then look at collecting the money itself.
Collect and Pay has fees. GOV.UK says 20% is added to what the paying parent pays, and 4% is taken off what the receiving parent gets. So if the maintenance due is £100, the paying parent pays £120, and the receiving parent receives £96. We checked these figures on GOV.UK on 30 October 2026. If you're in a Collect and Pay case and the other parent starts paying reliably, it's worth asking whether Direct Pay could work, because it saves both of you money.
What changes do I have to tell the CMS about?
You must tell the CMS about certain changes by law, as soon as they happen. GOV.UK lists these:
you change who the child's main carer is
you change the agreement on how often the child stays overnight
you want to change how you make and get payments
you move house (give your new address within 7 days of moving)
you change your bank details
you change your phone number or email address
you want someone else to deal with your case for you
you add a child to your case
the child is being adopted by someone else
you want to close your case
the child no longer lives in the UK
someone on the case dies
Either parent can also report it if the paying parent misses a Direct Pay payment, makes voluntary payments on top, has an income change of 25% or more (or no longer has an income), or is spending more or less money to see the child. Child maintenance ends when the child turns 20 or leaves approved education or training, whichever comes first. Any arrears built up before then can still be collected.
What if I don't agree with the CMS decision?
If you think the CMS has got something wrong, you first ask for a mandatory reconsideration. You must ask within 30 days of the date on the decision letter. The CMS looks at the decision again and writes to you with the result.
If you're still unhappy, you can appeal to the Social Security and Child Support Tribunal using form SSCS2. You have one month from getting the mandatory reconsideration decision. If you're late, you'll need to explain why. Set out clearly why you think the decision is wrong, with any evidence. You can choose to attend the hearing and explain your side, or ask for the appeal to be decided on the papers. Appeals can take some time to be listed, so it's best not to leave it to the last minute. Our guide to the child maintenance tribunal explains what happens at the hearing.
If your complaint is about how you've been treated, for example delays or lost paperwork, rather than the amount, use the DWP complaints procedure instead. If you feel you're going round in circles, our article on common problems with the Child Maintenance Service has practical suggestions.
How we can help
Court Help Limited is a family law paralegal firm in England and Wales. We're not solicitors and we don't represent clients in court. What we can do is help you understand your options, prepare a clear written statement for a mandatory reconsideration or an SSCS2 appeal, and organise your paperwork so your case is easy to follow. Email us at help@incourt.co.uk or use the contact form on this page. You can also read what other parents say about us in our Google reviews.
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Frequently asked questions
What is the CMS phone number?
The CMS phone number is 0800 171 2345 for cases in England, Scotland and Wales, open Monday to Friday, 8am to 6pm (checked on GOV.UK on 30 October 2026). The Welsh language line is 0800 232 1979, and Relay UK users dial 18001 then 0800 171 2345. Northern Ireland has a separate number on nidirect.
How long does the CMS take?
GOV.UK says the first payment is usually made within 12 weeks of applying. It can take longer if the CMS has trouble tracing the other parent or getting income details, so give it as much accurate information about the other parent as you can.
What is collect and pay child maintenance?
Collect and Pay is where the CMS collects child maintenance from the paying parent and passes it on to the receiving parent. It costs the paying parent an extra 20% and the receiving parent 4% of the amount due. With Direct Pay, the parents pay each other directly and there are no fees.
Do I have to use the CMS?
No. If you can agree an amount, a private arrangement works just as well and costs nothing. The CMS is there for when you can't agree, or when a private arrangement stops working.
Can the CMS take money from wages?
Yes. Under Collect and Pay, payments can be taken from the paying parent's earnings, bank account, benefits or pension. If payments are missed, the CMS can take further action to collect what is owed.
This article is general information about the law in England and Wales. It is not legal advice and should not be relied on as legal advice. Every case turns on its own facts, and court fees and procedures change, so check GOV.UK for the latest position. Court Help Limited is a family law paralegal firm, not a firm of solicitors, and does not represent clients in court.
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