What there is instead is an evidence test. The further back you want the correction to run, the more you have to show the conditions were met throughout.

One warning before you start. Council Tax Reduction is a different scheme with firm statutory limits, and can Council Tax Reduction be backdated deals with it separately.

There is no statutory maximum. Entitlement to a discount, an exemption or the disabled band reduction starts when the qualifying conditions were met, and a council can correct the account back to that point.

The word to hold on to is discretionary

No statutory ceiling is not the same as an automatic right to a correction running back a decade. How far back a council actually goes is discretionary and evidence-led, and practice varies between councils.

So no national period can be given, and any page that gives one is guessing. Ask your own council what it will do and on what evidence.

Four different rules, one question

Which rule is yours decides everything

A disregard never applied and a Council Tax Reduction claim made late are governed by completely different provisions. Which people are disregarded for council tax purposes sets out the first, and the rest of this page separates the others.

Because it has statutory periods and the discounts do not. Working age is up to 6 months on continuous good cause, and pension age is 3 months with no good cause test at all.

Six months is a ceiling, not an entitlement

Regulation 26(8) of the Council Tax Reduction (Scotland) Regulations 2021 takes the latest of three dates. Good cause that began nine months ago yields six months, and good cause that began three months ago yields three.

The good cause also has to be continuous right up to the date you applied. A period in the middle where you could reasonably have applied breaks the chain, and the backdate then runs only from the point it resumed.

The one-month rule you may have been told about is a different thing

Regulation 26(1) contains several automatic linking rules, each with a one-month window and no good cause test. They cover situations such as a qualifying benefit award, becoming liable for the first time, separating from a partner who was entitled, and notifying an intention to apply.

A council page describing that as backdating is describing the linking rules. A claimant told only about the one month is being under-advised by five.

The two mechanisms side by side

Entitlement starts on the later of the date of medical certification and the first day of entitlement to a qualifying benefit. That single rule is behind most of the disappointment on this subject.

A certificate can cover a past period

Paragraph 2(1)(b) of Schedule 1 to the 1992 Act requires a certificate stating that the person has been, or is likely to be, severely mentally impaired as regards a period including the day. That wording supports a certificate covering time already gone.

The certificate has to come from a registered medical practitioner, and the regulations do not say it must be your own general practitioner. What the severe mental impairment council tax exemption is sets out all three limbs.

Why the benefit date usually wins

In practice most Scottish councils tie backdating to benefit receipt rather than to diagnosis. That is the source of the widely reported gap in dementia cases, where a diagnosis long predates the disability benefit.

It is worth arguing the certification date where you can evidence it. Ask the council in writing which date it has used and why.

And check what the household was actually worth

Where every resident qualifies the dwelling is exempt rather than discounted, under Class 23 of the 1997 Order. Where one qualifying adult lives with one other adult the bill carries a 25% discount instead.

That is a different route again. A band is challenged by a proposal to the Assessor, and the time limit depends on the ground rather than on how long you have been overpaying.

When you can make a proposal

A fall in the market is not a material reduction, so it is not a ground at any time. How do you challenge your council tax band in Scotland sets the route out, and the Scottish Assessors Association publishes the bands.

What the Assessor has to do

The Assessor must acknowledge a proposal within 14 days and has 6 months to determine it. Where it is refused, or not decided in that time, the onward appeal to the Local Taxation Chamber runs to 6 months plus 6 weeks from when the Assessor received the proposal.

Where the appeals go now

The Valuation Appeal Committee and the Council Tax Reduction Review Panel both transferred to the Local Taxation Chamber of the First-tier Tribunal for Scotland on 1 April 2023. Liability and water charge appeals run to 4 months and penalty notices to 28 days.

In writing, naming the period, the ground and the evidence. Treat it as an application for a past period rather than as a complaint about the current bill.

What to put in the letter

• The address, the account reference, and the exact period you say was wrongly charged.
• Which discount, disregard, exemption or reduction you say applied, and why.
• Evidence covering the whole period rather than just today.
• Who else lived in the property during that period, because the discount depends on the adult count.
• A request that the council confirm in writing how far back it has agreed to go, and why, if it does not go the whole way.

Evidence that carries a past period

Benefit award letters with their start dates, a medical certificate covering a stated period, course certificates and tenancy agreements all do the job. Anything with a date range on it is worth more than a current statement.

The council has to correct a defective bill, but you still have to pay

Regulation 29 of the administration regulations requires a council that discovers a mistake in a demand notice to issue a statement of what was missing as soon as practicable. It does not give you a right to stop paying in the meantime.

It is first set against any other council tax you owe that council, and only the excess is repayable. Ask for the refund, because on most of the routes it is repaid to you only if you require it.

The four refund routes

Those routes are in the Council Tax (Administration and Enforcement) (Scotland) Regulations 1992, in force 1 April 1993. There is no time limit in those Regulations for claiming a repayment and none on the council for making one.

A credit left sitting is a credit you may forget

Where a council can either repay or credit, it decides unless you require repayment. If you want the money rather than a credit against next year, say so in the letter.

The official error rule almost nobody mentions

Where working-age Council Tax Reduction was overpaid because of an official error, and you could not reasonably have been expected to realise it, the resulting arrears are not recoverable at all. That is regulation 21 of SSI 2021/249, in force 1 April 2022.

It does not apply where you caused or materially contributed to the mistake. Where it does apply it is a complete answer to that part of the bill.

Get the correction applied first, then deal with what is genuinely left. A recalculated balance is a much easier thing to arrange than a disputed one.

Recovery does not pause while you argue

A council can apply for a summary warrant on an unpaid balance, and a 10% statutory addition goes on when it is granted. What happens if you do not pay your council tax in Scotland sets out the sequence.

A late bill is also not a void bill. Regulation 20(5) lets a demand notice be issued after the end of the year with no time limit in it, and how far back a council can chase council tax arrears deals with that question in full.

Ask for the account to be re-spread once it is corrected

There is no statutory maximum period for spreading council tax arrears, so a longer plan is a competent thing to ask for. How do you set up a council tax payment arrangement covers the approach.

And take the paperwork to a free adviser

An adviser will spot the discounts and reductions that were missed as well as the one you noticed. Our council tax debt advice page sets out how we help, and what free debt advice is available in Scotland lists the free services.