Child Maintenance Service contact number
The Child Maintenance Service line covers new applications, payments and changes for existing arrangements. You can also use your CMS online account for most of this.
Checked against gov.uk on 7 September 2026
Child Maintenance ServiceFree to call
Other ways to call
Welsh language line: 0800 232 1979
Relay UK (if you cannot hear or speak on the phone): 18001 then 0800 171 2345
Have this ready before you call
- Your National Insurance number
- Your CMS reference number, if you have one
- Details of the other parent, if you are applying
If the line is closed
- Your Child Maintenance Service online account handles payments, messages and changes around the clock
Common questions
Is the CMS number free?
Yes. 0800 171 2345 is free from UK mobiles and landlines.
Does this number cover Northern Ireland?
No. Northern Ireland has its own Child Maintenance Service with different contact details, listed on nidirect.gov.uk.