How to complain about the Child Maintenance Service
Last updated: 10/04/2025
You can make a complaint about the Child Maintenance Service (CMS) if you’re unhappy with the service you’ve had from them.
CMS Contact Details
Child Maintenance Service 21
Mail Handling Site A
Wolverhampton
WV98 2BU
Telephone: 0800 171 2345
Relay UK: 18001 then 0800 171 2345
Monday to Friday, 8.30am to 3.30pm
Calls are free from mobiles and landlines.
What can I complain about?
You can complain about things like:
- mistakes in the calculation
- a long delay dealing with your case
- delays in taking enforcement action
- difficulty contacting the CMS
- not providing you with a translator
- being discriminated against
You could ask them to:
- fix the problem
- admit they made mistakes and take steps to avoid them in future
- pay you compensation for distress or cost caused by delays or mistakes
How do I make a complaint?
This is the process that needs to be followed to make sure your complaint is dealt with correctly.
Talk to the person dealing with your child maintenance case
You first need to speak or write to the person dealing with your case or their manager. If you already have an online CMS account you can use webchat to talk to a CMS advisor. Tell them why you’re unhappy giving as much detail as possible.
If you call, keep a note of when you called, who you spoke to, and what you said.
If you write to the CMS put ‘Complaint’ at the top of your letter and keep a copy. You can also ask the Post Office for a Proof of Posting receipt.
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.
Ask for a review of how your complaint has been handled
If you are not satisfied 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.
Contact the Independent Case Examiner
You will receive a final decision about your complaint from the Complaints Resolution Team. If you still feel your complaint has not been resolved you can then contact the Independent Case Examiner (ICE). They are 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.
Complain to the Independent Case Examiner
Ask your MP to refer you to the Ombudsman
You can ask your MP/MSP to refer you to an ombudsman if you are not happy with the replies you have had from the CMS and ICE.
The Parliamentary and Health Service Ombudsman deals with complaints about the CMS.
Find your MSP at The Scottish Parliament
Help from your MP
You need your MP to refer you to the Parliamentary and Health Service Ombudsman but they may be able to help before you get to this stage. Your MP can contact the CMS on your behalf about a complaint or another problem.
Going to court if you can’t resolve your complaint
If you can’t get your complaint resolved in any other way you can consider asking a solicitor, or other legal service, about going to court.
You might need to go to court if your family has been affected by how the CMS has handled your case. This could be something like a reduction in how often you can see your children because the CMS have taken so long to calculate child maintenance.
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 you feel they have disregarded the law by not considering everything they should have or by doing something they should not have.
Going to court could be expensive. You might have to pay court fees and for the services of a solicitor.