Guide · Updated 07/07/2026 · Deadline: 1 month from the decision letter

Mandatory reconsideration

Before you can appeal any CMS decision to the independent tribunal, you must first ask the CMS to look at it again. This is the mandatory reconsideration (MR) — free, quick to request, and the point at which a large share of errors get fixed. It is also where parents most often lose their rights by missing the clock.

What can go to MR

Any decision: the maintenance calculation, the income figure used, shared care banding, a variation grant or refusal, a supersession refusal, the effective date, an arrears-related decision, a default maintenance decision. What cannot: complaints about service, delay or conduct — those go up the complaints ladder instead (and can run in parallel).

The clock

How to do it well

1. Request it in writing

   Phone is valid but leaves you dependent on their note of the call. Write — via your online account message facility or letter — so the date and content are provable. State plainly: "I request a mandatory reconsideration of the decision dated [date]."

2. Identify the specific decision

   Quote the letter date and reference. If several decisions are in play (calculation plus arrears, say), name each one — each carries its own MR right.

3. Say exactly what is wrong, by element

   Not "this is unfair" but "the gross income of £X is wrong: my P60 for 2024/25 shows £Y" or "shared care Band B applies: the attached court order provides 2 nights weekly". Point to the rule — the calculation guide and income guide give you the framework.

4. Attach evidence

   P60s, payslips, pension statements, court orders, care diaries, bank statements. The single biggest difference between MRs that succeed and fail is documentary evidence. If evidence will take time to gather, lodge the request inside the month and send evidence after — the deadline attaches to the request.

5. Ask for the decision-maker's working

   Request the figures, tax year, and calculation steps used. This either resolves the case or builds your appeal bundle. Consider a parallel subject access request for the full file.

6. Diarise the outcome

   You will receive a Mandatory Reconsideration Notice (MRN) — usually two copies, because you need to send one with any appeal. The MRN date starts your one-month tribunal appeal clock. There is no fixed statutory time limit for the CMS to complete an MR; if it drags for months, chase in writing and consider a complaint about the delay.

Template letter

Adapt every bracketed section. Full set of templates here.

Outcomes and next steps

Three possibilities: the decision is changed in your favour, changed against you (rare but possible — reconsideration is a fresh look), or unchanged. If you remain unhappy, the MRN unlocks the First-tier Tribunal — an independent judicial body with a materially better track record of correcting CMS errors than the internal process. Do not be discouraged by an unchanged MR; treat it as the qualifying step it is.