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If you disagree with a CMS decision

Use this page when the amount looks wrong — for example income period, shared care nights, or arrears. Complaints about poor service are a separate route (Guides → Complaints & ICE).

Deadlines are short. Note them the day a letter arrives. Late applications can sometimes be accepted — explain the delay in writing and keep proof of posting or online submission.

Back to Start here Open breakdown letter

Which stage are you at?

I just got a decision letter

Start with a written calculation breakdown, then MR within usually 30 days.

I already asked for a breakdown

If the figure is still wrong, request mandatory reconsideration with evidence.

I have an MR notice and still disagree

Appeal to the Social Security and Child Support Tribunal (SSCS2), usually within one month.

Enforcement started during the dispute

Keep the dispute going and follow the enforcement guide in parallel.

1) Ask for a written explanation

  1. Note the income figure, tax year/period, rate band, and shared care nights on the letter.
  2. Run the estimate calculator with the same inputs.
  3. Request a full calculation and arrears ledger in writing.
  4. Log the request date in your case timeline or My Case.

Breakdown letter Calculator

2) Mandatory reconsideration

  1. Usually within 30 days of the decision letter date.
  2. State clear grounds (wrong income period, shared care, missing payments, and so on).
  3. Attach or list evidence — do not rely on CMS to find it.
  4. Keep the mandatory reconsideration notice when it arrives.

MR letter Figure-jump guide

3) Tribunal appeal (SSCS2)

  1. Usually within one month of the MR notice.
  2. Complete form SSCS2 and post it to HMCTS with your evidence pack — child maintenance appeals are not the general online benefit-appeal flow.
  3. Include a date list (timeline download) and a numbered evidence list.
  4. Use a cover note to summarise grounds and the outcome you want.

Tribunal cover note SSCS2 form (GOV.UK) Export evidence pack

Evidence checklist

Full checklist: Guides → Evidence.

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