Complaining about the Child Maintenance Service

This advice applies to England. See advice for See advice for Northern Ireland, See advice for Scotland, See advice for Wales

You can make a complaint if you’re unhappy with the service you’ve had from the Child Maintenance Service (CMS). 

If you’re unhappy with a decision they’ve made, you should ask for a review. 

Find out how to ask for a review if you’re getting child maintenance

Find out how to ask for a review if you’re paying child maintenance

Check if you can complain

The kinds of things you can complain about include:

  • mistakes - for example, if they lose your documents

  • a long delay dealing with your case

  • bad advice - like mistakes in the calculation or not explaining arrears figures 

  • delays in taking enforcement action

  • difficulty contacting the CMS - for example, if you have to wait a long time before talking to someone

  • not providing you with a translator

  • being discriminated against - find out more about discrimination by public organisations

Think about what you want the CMS to do

Before you complain you should have an idea of what you want the CMS to do.

You could ask them to:

  • apologise to you

  • fix the problem

  • explain what went wrong

  • change the way they do things - this will help other people

  • pay you compensation

Making a complaint to the CMS

You should contact the CMS. You can call or write to them. You can also contact the CMS using your online account, if you have one. You’ll need the 12-digit reference number that begins with ‘121’ on any letters the CMS has sent you. You can access your online account on GOV.UK.

Ask to speak to or write to the person dealing with your case or their manager.

Tell them why you’re unhappy. Give them as much detail as you can. It’s best to write so you have a written record of your complaint. 

If you call, make a note of:

  • who you spoke to

  • when you called

  • what each of you said

  • any action the CMS said they’d take

If you write, put ‘Complaint’ at the beginning of your letter. Keep a copy of your letter and any reply you get - you might need them if you need to take your complaint further. 

You should give full details of your complaint at every stage. The person who dealt with the complaint earlier might not have passed on all the information.

Check what to include in your complaint

You should include, if possible:

  • your name, address, date of birth, CMS reference number and contact details

  • photocopies of any correspondence - make sure you keep the originals

  • a summary of the complaint and accurate details of dates and events - like dates of phone calls and contacts with CMS staff

  • any other documents relating to your complaint

  • an explanation of why you’re not happy with the way you were treated

Sending your complaint

You should send your complaint to:

Child Maintenance Service

Child Maintenance Service 21

Mail Handling Site A


WV98 2BU

Telephone: 0800 171 2345

Welsh language: 0800 232 1979

Relay UK - if you can't hear or speak on the phone, you can type what you want to say: 18001 then 0800 171 2345

You can use Relay UK with an app or a textphone. There’s no extra charge to use it. Find out how to use Relay UK on the Relay UK website.

Monday to Friday, 8am to 6pm

Calls are free from mobiles and landlines.

If you’re sending a letter, ask the Post Office for free proof of postage - you might need to show when you sent it. 

Getting a decision about your complaint

You should get a letter saying the CMS has received your complaint within 2 working days. 

The CMS will try to deal with your complaint within 15 working days. If it’s likely to take longer, they’ll tell you and agree a new timescale with you. 

If you’re still not happy with the response from the CMS

You can take further steps to try to get your complaint resolved. They’re all free. 

Step 1: complain to the Complaints Resolution Team

Contact the CMS Complaints Resolution Team if you’re not happy with the CMS response to your complaint. You’ll find their contact details on any letter you’ve had from the CMS. 

Step 2: ask for a review

If you’re unhappy with the reply from the Complaints Resolution Team, you can ask for a review. The review will look at how your complaint has been dealt with and what else can be done. You’ll find contact details in the letter from the Complaints Resolution Team.

Step 3: contact your MP

You can contact your local MP of your complaint. It might get you a quicker reply from the CMS. Your MP could:

  • advise you on whether to take the complaint further

  • try to get the law changed if you’re unhappy about the law on child maintenance

  • refer your complaint to the ombudsman

  • help with a decision you can’t appeal against

MPs can also help progress your case if the CMS isn’t replying to your letters or taking too long to take action. For example, they could get: 

  • enforcement action started if you’re owed maintenance

  • a deduction from earnings order reduced if you’re being asked to pay too much and this is causing you hardship

Step 4: contact the Independent Case Examiner

If you still haven’t been able to resolve your complaint, the CMS will send you a letter with their final decision. The letter will also say you can take your complaint to the Independent Case Examiner (ICE). They’re not part of the CMS.

You must make your complaint to the ICE within 6 months of getting the final decision from the CMS. You’ll need to send a copy of that decision with your complaint. 

You can find out more about making a complaint to the ICE on GOV.UK. 

Step 5: contact the ombudsman

An ombudsman is an independent person who looks into complaints about organisations. There are different ombudsmen for different organisations. 

The Parliamentary and Health Service Ombudsman deals with complaints about the CMS. You can’t contact the ombudsman directly - you’ll need a referral from your MP. 

You should try and resolve your complaint with the CMS before you complain to an ombudsman. 

You can read more about complaining to an ombudsman

Getting compensation

You might be able to get compensation if:

  • you’ve had to pay for things like call costs or bank charges

  • the CMS has taken too long in dealing with you - like not replying to letters

  • the CMS has caused you severe distress,  inconvenience or embarrassment

You could also get compensation if you’re getting maintenance and you’ve lost out financially because of delay by the CMS. 

If you want compensation, you should say so when you make your complaint. If you’ve had to pay extra call costs or bank charges, you’ll have to show how much - for example, with an itemised bill or a bank statement.

If you’re not sure if you can get compensation, talk to an adviser.

Going to court if you can’t resolve your complaint 

If you can’t get your complaint resolved in any other way, you might consider going to court. Going to court is likely to cost you money. You might have to pay court fees and for the help of a lawyer. 

You might need to go to court if your right to a private and family life has been affected - for example, if something the CMS has done is stopping you seeing your children or limiting how much you can see them. You can read more about your right to a private and family life.

You might also need to go to court if you want to challenge the CMS through a process called ‘judicial review’. You can do this if:

  • the CMS did something they don’t have the power to do

  • the CMS disregarded something that was relevant or took into account something irrelevant

  • the CMS didn’t follow their own procedure

If you want help with a judicial review, you’ll need a solicitor. You can talk to an adviser to find legal help. 

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Page last reviewed on 27 October 2020