Guide · Updated 07/07/2026

Subject access requests: get the file

Under Article 15 UK GDPR and the Data Protection Act 2018 you can require the DWP to hand over the personal data it holds about you — including CMS case notes, call records, decision rationales and the income figures actually used. It is free, they have one month, and it is routinely the most illuminating document set in any dispute.

What you get

• Case notes and contact history — every call summary, every action (and every inaction);
• The income figures obtained from HMRC, and the tax years they relate to;
• Shared care determinations and what evidence was recorded;
• Decision and calculation records, arrears ledgers, enforcement referrals;
• Copies of correspondence and, where they exist and you ask, call recordings.

You receive your personal data: the other parent's information will be redacted, as will some internal material. Expect redactions; challenge excessive ones via the ICO if needed.

How to make the request

1. Send it in writing

   To the DWP as data controller — via your online CMS account message, by post to the address on your letters, or through the DWP subject access request route on GOV.UK. Include full name, address, date of birth, National Insurance number and CMS case reference.

2. Specify scope — broadly but usefully

   "All personal data held by the Child Maintenance Service in relation to case [ref], including case notes, telephone call summaries and recordings, maintenance calculation records, income data obtained from HMRC, shared care determinations, arrears ledgers and enforcement records, for the period [dates]." A defined period speeds things up; you can always ask again.

3. Diarise one month

   The DWP must respond within one calendar month (extendable by two more for complex requests — they must tell you within the first month). Silence past the deadline: complain to DWP, then to the ICO, which is free and effective.