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SMI Council Tax Relief — No Time Limit for Backdating

By GetRighted Legal Research TeamLast updated July 2026

Summary

There is no time limit for applying for the Severe Mental Impairment council tax disregard or exemption. Unlike some benefits with strict claim windows, SMI relief under SI 1992/548 Article 2 can be claimed at any time and backdated to the date both conditions — the medical certificate and the qualifying benefit — were first simultaneously satisfied. If a family member has had dementia for years and a qualifying benefit throughout, you can claim the full period and request a substantial refund.

How Backdating Works for SMI

The SMI disregard applies from the date both the medical condition and the qualifying benefit were in place. If the GP confirms the impairment existed from 2019, and the person has been receiving attendance allowance since 2018, the disregard starts from 2019 (when both limbs were met). The billing authority must recalculate bills for every year from that date forward and refund any overpayment. For a sole-occupant SMI person, this means a refund of 100% of council tax paid during the exempt period.

GP Certificates Can Be Backdated

Ask the GP to state in the medical certificate the date from which, in their clinical opinion, the person has had a severe impairment of intelligence and social functioning. GPs can and do backdate this assessment based on medical records. The earlier the confirmed onset date, the further back the relief — and the refund — extends.

Scale of Unclaimed Relief

Alzheimer's Society research estimates that hundreds of thousands of households eligible for SMI council tax relief are not claiming it. With average Band D council tax at approximately £2,100, each year of unclaimed relief represents over £2,000 in overpayment. For households that have been eligible for five or more years, refunds of £10,000+ are not uncommon when the relief is finally claimed and backdated.

If the Council Resists Backdating

Some billing authorities apply arbitrary backdating limits — one year, two years, or the start of the current financial year. These limits have no statutory basis. LGFA 1992 does not impose any cap on retrospective application of discounts or exemptions. If the council refuses to backdate to the correct start date, submit a formal dispute under s.16 and, if necessary, appeal to the Valuation Tribunal for England.

Sources

  1. Council Tax (Discount Disregards) Order 1992, SI 1992/548, Article 2
  2. Local Government Finance Act 1992, ss.11, 16

Frequently Asked Questions

My father had Alzheimer's for 8 years before we knew about SMI relief — can we really claim all 8 years?
Yes, provided the GP can certify the impairment existed for that period and a qualifying benefit was in payment throughout. Request the GP to state the clinical onset date. The council must recalculate and refund the entire period.
The qualifying benefit was only awarded last year but the condition existed for longer — from when does relief apply?
Relief starts from the later of the two dates: the medical certificate date or the benefit award date. If the benefit was only awarded last year, relief starts from the benefit award date — even if the impairment predates it. Consider whether the benefit itself can be backdated through a DWP mandatory reconsideration.
Does the council have to pay interest on the refund?
No. Council tax refunds do not carry statutory interest. The refund is the difference between what was paid and what should have been charged — no more. This is another reason to claim as soon as you become aware of the entitlement.

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