How to Appeal a UK Child Maintenance CMS Decision

To appeal a CMS child maintenance decision, you first have to ask the Child Maintenance Service to look at its decision again through a mandatory reconsideration, and then, if you still disagree, appeal to the First-tier Tribunal (Social Entitlement Chamber) using form SSCS2. Each stage has a one-month deadline, and skipping the reconsideration means the tribunal will not hear you.¹

Start With a Mandatory Reconsideration

The reconsideration is a legal prerequisite under the Child Support Act 1991. You have one month from the date on your CMS decision letter to ask for it, either by phone or in writing to the address on the notice. A different caseworker checks whether the income figures, shared care nights, and other facts were recorded correctly.

When the review finishes, the CMS sends you a Mandatory Reconsideration Notice saying whether the decision has been changed and why. Keep that notice safe. It is your ticket to the tribunal, and you cannot file an appeal without it.

If You Missed the One-Month Window

A late request is still possible for up to 13 months after the original decision, provided you give a good reason for the delay, such as a hospital stay or serious illness. The further past the deadline you are, the stronger that reason needs to be. If the CMS refuses to accept a late reconsideration, you can generally appeal that refusal to the tribunal so long as you acted within the 13-month window.²

What You Can Actually Argue

The tribunal is not a fresh negotiation about what feels fair. A judge checks whether the CMS applied the Child Support Maintenance Calculation Regulations 2012 correctly to the facts that existed when the decision was made.³ Section 20(7) of the Child Support Act 1991 stops the tribunal from taking account of anything that happened after the decision date.¹ If your income has since dropped, that is a matter for a new application to the CMS, not this appeal.

Most appeals come down to one of three issues.

Wrong Income Figures

The CMS pulls income data from HMRC, which is often out of date or based on the wrong tax year. If the figure used does not reflect what you actually earned at the relevant time, the tribunal can order a recalculation. Gather payslips, P60s, and self-assessment returns covering the period the decision relates to.

Wrong Effective Date

When a change in circumstances triggers a new calculation, the effective date the CMS assigns determines when the new amount starts. A date that is off by a few weeks can produce hundreds of pounds of arrears or overpayment. Delays in the CMS recognising a shared care change or an income shift are common reasons to challenge the effective date.

Variation Refusals

Where the standard HMRC-based calculation misses income, the receiving parent can apply for a variation. If the CMS refused a variation without properly justifying it, that refusal can be appealed. Variations cover unearned income (dividends, rental, interest of £2,500 or more a year that is chargeable to tax), assets over £31,250 after any mortgage, diversion of income (for example, through a company the paying parent controls), and earned income that is not being captured because someone on the nil or flat rate is actually earning more than £100 a week. The CMS must also decide whether a variation is “just and equitable.”⁴ Paying parents can apply for variations in the opposite direction where they have special expenses such as contact travel, boarding school fees, or debts from before the separation, provided those expenses equal or exceed £10 a week.⁵

Filing the Appeal on Form SSCS2

Child maintenance appeals use form SSCS2. This is a common trap: the SSCS1 form used for other social security benefits does not apply here, and the SSCS1 itself says so on its face.⁶ Filing the wrong form will delay your case. You can download the SSCS2 from GOV.UK or request one from His Majesty’s Courts and Tribunals Service.⁷

You have one month from the date on the Mandatory Reconsideration Notice to submit the appeal.² Before you start, have your CMS case reference number and the date on the reconsideration notice to hand.

The form asks why the decision is wrong. General dissatisfaction will not carry an appeal. Say specifically which facts the CMS got wrong or which part of the regulations it misapplied. On an income point, state the figure the CMS used and the figure you say is correct. On a shared care dispute, state how many nights the child actually spends with each parent and what evidence supports that count.

Attach the paperwork that backs each claim: payslips, P60s, bank statements, tax returns, school records, calendars showing the child’s living pattern. Judges rely heavily on documents.

The form also asks whether you want an oral hearing or a paper decision. An oral hearing lets you answer the judge’s questions and respond to anything new the CMS raises in its written response. It suits complicated financial situations. A paper hearing tends to be faster but decides everything on the documents alone. Sign, date, and submit the completed form by post or through the online appeal portal.

At the Tribunal

Once you file, the tribunal sends a Notice of Appeal to both sides. The CMS prepares a formal response setting out its position, the evidence it used, and the legal basis for the decision, and you receive a copy before the hearing.

If you asked for an oral hearing, you can attend in person at a hearing centre or join by video or telephone.⁸ The judge may ask about your income, the child’s living arrangements, and the timeline of events. Parents who walk the judge through their documents and tie each one to a specific error in the calculation tend to do better than those who argue that the outcome feels unfair.

You do not need a solicitor. A friend or family member can sit with you as a “McKenzie friend” to take notes, help with papers, and quietly advise, but they cannot address the judge unless the tribunal grants permission, which is rare. A solicitor or other qualified representative can speak on your behalf as of right.

Two limits worth keeping in mind. The tribunal only looks at facts as they stood on the date of the CMS decision, so anything that has changed since then has to be reported separately to the CMS. And the tribunal will focus on the errors you raise, so make sure every point you want corrected appears clearly on the form.

After the Decision

The tribunal issues a written decision notice. If the judge finds an error, the tribunal can either substitute its own calculation or send the case back to the CMS with directions on how to reassess.¹ The result is legally binding, and the CMS must adjust future payments accordingly.

If the appeal is dismissed, the CMS decision stands. Before deciding whether to go further, request a written statement of reasons from the tribunal. This document sets out the judge’s legal reasoning in detail, and you must ask for it within one month of the decision notice.

Taking It to the Upper Tribunal

You can seek permission to appeal to the Upper Tribunal only on a point of law. That means the First-tier Tribunal applied the law incorrectly, breached procedure, or failed to give adequate reasons.⁹ Disagreeing with how the judge weighed the evidence is not a point of law.

Request the statement of reasons if you have not already. You then have one month from the date it was issued to apply for permission, first to the First-tier Tribunal itself. If it refuses, you can apply directly to the Upper Tribunal within one month of that refusal.¹⁰ Getting past the permission stage is the hardest part of the whole process, so the statement of reasons is where any Upper Tribunal case has to start.

1
Legislation.gov.uk. Child Support Act 1991 – Section 20
2
GOV.UK. Child Maintenance Service – Complaints and Appeals
3
Legislation.gov.uk. The Child Support Maintenance Calculation Regulations 2012
4
GOV.UK. How We Work Out Child Maintenance
5
GOV.UK. Volume 3 – Variations (Chapters 27-36)
6
GOV.UK. SSCS1 – Benefit Appeal Form
7
GOV.UK. Appeal a Child Maintenance Group Decision by the DWP – Form SSCS2
8
Courts and Tribunals Judiciary. Social Entitlement Chamber
9
GOV.UK. How to Appeal Against a Child Maintenance Decision – SSCS2 Guidance
10
House of Commons Library. Appealing Benefits Decisions Beyond the First-Tier Tribunal