Parents ask this question when they have run out of caseworkers to speak to. The answer matters, because the CMS is structured in a way that makes it genuinely hard to find a person with the authority to fix your case.

The CMS is not an agency

This is the first thing to understand, and it changes what your options are.

The old Child Support Agency was an executive agency. It had a chief executive, its own annual report and a degree of separation from the department above it. When it closed, that structure went with it.

The Child Maintenance Service is a directorate inside the Department for Work and Pensions. It has no chief executive, no separate legal identity and no board of its own. Legally, every decision the CMS makes is a decision of the Secretary of State for Work and Pensions. When your calculation letter says the CMS has decided something, the decision maker in law is the Secretary of State, acting through an official.

Why this is useful to you: There is no CMS chief executive to write to. But because every CMS decision is legally the Secretary of State's decision, a letter to the Secretary of State about your case is not a category error. It is addressed to the actual decision maker, and it usually gets routed to a ministerial correspondence team that operates outside the normal caseworker queue.

The chain of accountability

  1. Secretary of State for Work and Pensions. Legally responsible for every CMS decision. Accountable to Parliament.
  2. The DWP minister with the child maintenance brief. A junior minister, usually the Parliamentary Under-Secretary covering social security. This is the person who answers written parliamentary questions about the CMS and who your MP writes to on your behalf.
  3. The Director of the Child Maintenance Service. The senior civil servant running the service, responsible for strategy and performance. Simon Hunter held this post when DWP officials gave evidence to the House of Lords Public Services Committee on 19 March 2025.
  4. Deputy directors. The brief is split. At the March 2025 session, Duncan Gilchrist covered child maintenance policy, Chris Smith covered delivery assurance and modernisation, and Elaine Squires covered income, family and disadvantage analysis.
  5. Operational management and caseworkers. The people you actually speak to, working to guidance they did not write and cannot depart from.

We have written up what those officials told the Lords, and where their account diverges from the department's own published figures, in our piece on the March 2025 House of Lords evidence session.

Note on names: Senior civil service posts change hands. Names here are recorded with the date and source we saw them attached to that role, rather than presented as current. Before writing to a named individual, check the current post holder on GOV.UK or in a recent Hansard entry. The structure below is stable even when the names are not.

Who is not in charge

Two common assumptions are wrong, and both cost parents time.

The caseworker cannot use discretion. The formula is statutory. A caseworker cannot lower your payment because your rent went up, cannot waive fees because the service failed you, and cannot ignore an HMRC figure they can see is out of date. Escalating a formula complaint through the phone line will not work, because nobody on that line has the power you are asking them to use.

The courts have almost no role. Section 8 of the Child Support Act 1991 removes the courts' jurisdiction over child maintenance in most cases. A family judge cannot set your maintenance figure. The exceptions are narrow: top-up orders where income exceeds £156,000 a year, school fees, costs relating to a child's disability, and cases where both parents want a consent order.

Who checks the CMS

Five bodies sit outside the CMS and can look at what it does. They have very different powers, and picking the wrong one wastes months.

BodyWhat it can doWhen to use it
First-tier Tribunal (Social Entitlement Chamber) Overturn the calculation itself. Independent judge. Free. You think the figure is wrong. Requires a mandatory reconsideration first.
Independent Case Examiner (ICE) Investigate how you were treated and recommend redress. Service failure, delay, or poor handling. After the CMS complaints process.
Parliamentary and Health Service Ombudsman Final escalation for maladministration. Requires an MP referral. After ICE, if you are still not satisfied.
National Audit Office Audit the CMS Client Funds Account and publish findings. Not a route for individuals, but its reports are citable evidence.
Work and Pensions Committee Question ministers and officials in public, publish reports. Not a route for individuals. Its evidence sessions are public and searchable.

Who actually builds the system

The CMS does not write its own software. The CMS2012 case management system is maintained under contract by Tata Consultancy Services, on a contract worth around £60 million renewed in August 2024. Your income data arrives from HMRC through an automated feed. Your bank details, employer records and payment schedules all sit inside a platform built over a decade ago.

That matters more than it sounds. A large share of the errors parents report are not caseworker decisions at all. They are data problems: an HMRC figure from the wrong tax year, an employer record that never updated, a shared care count that was entered once and never revisited. We have set out how the technology fits together in inside the CMS system.

How to reach someone with authority

In the order that actually works.

  1. Mandatory reconsideration. If your complaint is about the figure, this is the only route that leads anywhere. One calendar month from the decision date, and you cannot appeal without it. Our letter generator builds one and calculates your deadline.
  2. Formal complaint to the CMS. If your complaint is about service, delay or how you were treated. Put it in writing, quote your case reference and state what outcome you want.
  3. Your MP. The single most effective step most parents can take. MPs write directly to the DWP minister holding the child maintenance brief, and those letters are tracked and answered on a deadline. Our complaints letter generator finds your MP from your postcode and copies them automatically.
  4. Independent Case Examiner. Once the CMS complaints process is exhausted, or after 15 working days with no resolution.
  5. First-tier Tribunal. Free, independent, and the judge can overturn the CMS. This is the only body that can change your calculation against the department's wishes.
Do not skip step one. Complaining about a figure through the complaints process instead of a mandatory reconsideration is the most common wasted month we see. The complaints process cannot change a calculation. Only a reconsideration, and then a tribunal, can. The one month deadline runs while you are in the wrong queue.

Checking any of this yourself

  • Hansard at hansard.parliament.uk. Search "Child Maintenance Service" to see which minister is currently answering, and what they have said.
  • Written parliamentary questions at questions-statements.parliament.uk. Often the only public source for CMS figures that are not otherwise published.
  • Committee evidence at committees.parliament.uk. Transcripts and video of officials being questioned under their own names.
  • DWP statistics on GOV.UK, published quarterly, covering caseload, compliance and arrears.
  • WhatDoTheyKnow at whatdotheyknow.com, for FOI requests and responses. We index the CMS ones on our FOI page.