Mandatory Reconsideration Letter Generator

The month runs from the date on the letter, not the day it arrived

One calendar month. A decision dated 3 March has to be challenged by 3 April. The date the envelope landed on your doormat is irrelevant, and so is the date you opened it.

That matters more than it sounds, because the CMS dates a decision when the caseworker makes it and posts it afterwards. Four or five days of your month can be gone before you know a decision exists. Check the date at the top of the letter first, work out your deadline second, then decide what to write.

Send it by recorded delivery or through your CMS online account, and keep the proof. If you phone the request through, note the date, the time and the name of the person who took it, then confirm it in writing the same day. Requests made only by phone have a habit of not appearing on the file.

Missing the month does not end everything. The CMS can accept a late request for up to 13 months where there are special reasons: a hospital admission, a bereavement, serious illness, a decision letter posted to an address you had already told them you had left. It is discretionary. They can say no. Treat it as a rescue, never as a plan.

A complaint cannot change your calculation. Only a reconsideration can

This is the costliest mistake in the whole system, and it is entirely understandable. The figure looks wrong, a phone call goes badly, and the obvious response is to complain. The complaint is logged. A reply arrives weeks later apologising for the delay in replying. By then the reconsideration window on the decision you actually wanted changed has shut.

The two routes do completely different jobs. A mandatory reconsideration attacks the decision: the income used, the number of qualifying children, the shared care nights, the effective date. The complaints process attacks the service: delay, rudeness, lost documents, being told something that was not true, a caseworker who sat on evidence you supplied. A complaint handler cannot lawfully alter a maintenance calculation. They have no power to do it, however sympathetic they are.

Running both at once is often the right answer. If a caseworker ignored the payslips you sent in January and the calculation came out on the wrong income, the wrong income is a reconsideration point and the ignoring is a complaint point. Do the reconsideration first, because that is the one with a clock attached.

What a reconsideration can fix, and what it cannot

Reconsiderations succeed when they point at a fact the CMS got wrong. They fail when they argue with the rules themselves.

Grounds that can win

• The wrong income figure: the wrong tax year pulled from HMRC, pay from an employer you left, a bonus counted twice, or pension contributions missing from the gross figure. The rules on what counts as income are narrower than most parents expect
• The wrong number of shared care nights. This works in bands, not night by night: 52 to 103 nights takes a seventh off, 104 to 155 takes two sevenths, 156 to 174 takes three sevenths, and 175 or more halves the figure then knocks a further £7 a week off it
• The wrong number of qualifying children, or other children living in your household not being counted. Those should cut your assessed income by 11%, 14% or 16%
• The wrong effective date, which changes how much is owed and from when
• A variation you applied for that was never decided, or was refused without the evidence being looked at

Grounds that cannot win

• The percentages. 12% for one child, 16% for two and 19% for three or more across the basic band of £200 to £800 gross weekly income sit in the Child Support Maintenance Calculation Regulations 2012
• The use of gross income rather than net. Tax and National Insurance are not taken off before the percentage is applied, and that is deliberate
• Your rent, your mortgage, your commuting costs, your debts. None of them are deductible
• The other parent's spending, conduct, or new partner's income

If your objection sits on the second list, a reconsideration will not help and neither will a tribunal, because the tribunal applies exactly the same regulations. That argument belongs to politicians, which is why the House of Lords has been examining how the formula works.

Evidence that actually moves a decision

A reconsideration is decided on paper, usually by someone who had nothing to do with the original decision. They are looking for a document that contradicts what is on the file. Your job is to hand them one.

Assertion on its own rarely works. "My income is not £48,000" gets you a letter back saying HMRC says it is. A P60 showing £41,200 gets the figure changed. Self employed cases are harder because the CMS starts from the HMRC record rather than your books, and the way self employed income is assessed is worth understanding before you write.

What comes back, and what to do with it

The CMS issues a Mandatory Reconsideration Notice. It either changes the decision or confirms it. Keep that notice safe, because the tribunal service will ask for it and will not accept an appeal without it.

Turnaround varies. Some come back in a fortnight, some take considerably longer, and the general pattern of CMS processing times applies here too. If the reconsideration itself drags on for months with no updates, that delay is a service failure, and the complaints route is the right place for it while the reconsideration continues.

If the notice changes the figure, check the arrears position as well as the weekly amount. A corrected calculation usually needs the balance recalculated back to the effective date, and the two do not always update together. The arrears calculator is a quick way to see whether the new balance makes sense.

The tribunal is free, independent, and you can run it yourself

If the notice confirms the original decision, the next step is the First-tier Tribunal, Social Entitlement Chamber. You have one month from the date on the Mandatory Reconsideration Notice to lodge the appeal, using form SSCS1 or the online service.

It costs nothing. It is not part of the DWP, and the judge is not reviewing whether the CMS followed its own internal guidance. The judge decides what the correct decision should have been and can substitute their own, which is a genuinely different exercise from asking the CMS to mark its own homework. Panels usually include a judge and a member with financial expertise, and hearings run in person, by telephone or by video.

Most parents represent themselves and do it perfectly well. Bring a short chronology of dates, the documents you sent to the CMS, and one clear sentence on what figure you say is right and why. Answer the questions you are asked rather than the ones you prepared for. Tribunals deal with facts and regulations, so leave the history of the relationship out of it.

One boundary worth knowing. Section 8 of the Child Support Act 1991 removes the family court's jurisdiction over routine maintenance, and section 33(4) stops a magistrates' court from questioning whether a calculation is correct when a liability order comes before it. In practice the tribunal is the only forum that can look at your figure at all, which is why the one month reconsideration deadline is worth guarding so carefully.

Common questions