Severe Mental Impairment Council Tax Discount: Full Guide for 2026/27
A person with a severe mental impairment, such as advanced dementia, can be disregarded entirely for Council Tax purposes. How to qualify, apply and backdate the SMI discount in 2026/27.
Quick answer
If someone in the household has a permanent severe mental impairment — most commonly dementia — and receives a qualifying disability benefit, they can be "disregarded" for Council Tax, meaning the bill is calculated as if they weren't a resident at all. Combined with living arrangements, this can mean anything from a 25% reduction to a full 100% exemption, and it's frequently under-claimed simply because families don't know it exists.
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Council Tax calculatorThe two-part eligibility test
Both of the following need to be true:
- Medical evidence — a GP or psychiatrist certifies the person has a severe impairment of intelligence and social functioning (however caused) that appears to be permanent.
- Qualifying benefit — the person is entitled to at least one of a specific list of benefits, most commonly the middle or higher rate care component of Disability Living Allowance, the daily living component of Personal Independence Payment, Attendance Allowance, or certain other listed qualifying benefits.
Both parts are needed — a diagnosis alone, without the qualifying benefit, doesn't unlock the discount, and vice versa.
How much it actually saves
Because someone with SMI is disregarded, not just "discounted", the effect depends on who else lives in the property:
- Living alone with SMI: 100% Council Tax exemption.
- Living with one other adult who isn't themselves disregarded: the bill drops to the 25% single-person discount rate, as if only one countable adult lived there.
- Living with two or more other countable adults: SMI alone may not reduce the bill, though the household should still check for other applicable discounts.
Applying, and backdating
Applications go through the local council, usually requiring the GP certificate and proof of the qualifying benefit award. Many councils will backdate the discount to the date all conditions were first met — which, for a condition like dementia that develops gradually and is sometimes diagnosed well after symptoms begin, or where a family simply didn't know to apply, can mean a substantial multi-year refund once granted.
Bottom line
If a family member has dementia, a severe learning disability, or comparable permanent cognitive impairment, and receives a qualifying disability benefit, check SMI Council Tax eligibility directly with the local council — it's a genuinely valuable, frequently missed reduction, and backdating can recover money already overpaid.
Sources
- GOV.UK: Council Tax discounts and reductions
- Alzheimer's Society: Severe Mental Impairment Council Tax discount
Frequently asked questions
What conditions qualify for the Severe Mental Impairment Council Tax discount?
Conditions causing a severe, permanent impairment of intelligence and social functioning can qualify — commonly dementia (including Alzheimer's), Parkinson's disease with associated cognitive impairment, severe learning disabilities, and the effects of a serious stroke or brain injury, provided the specific medical and entitlement criteria are met.
What two things do I need to prove SMI eligibility?
You need a doctor's certificate confirming the person has a severe mental impairment that is permanent, and evidence they are entitled to at least one specific qualifying benefit (such as the middle or higher rate of the care component of Disability Living Allowance, the daily living component of Personal Independence Payment, Attendance Allowance, or certain other listed benefits).
How much discount does SMI give?
A person with SMI is 'disregarded' for Council Tax purposes, meaning they don't count as a resident adult. If they live alone, this can produce a 100% Council Tax exemption. If they live with one other adult who isn't disregarded, the household gets the 25% single-person discount as if only one adult lived there. If they live with two or more other counted adults, there may be no discount from SMI alone, though other discounts could still apply.
Can the discount be backdated?
Yes, often significantly — many councils will backdate the SMI discount to when the person first met all the qualifying conditions (the diagnosis and the qualifying benefit), which can sometimes mean years of retrospective discount if the application wasn't made promptly at the time.
Do I need to reapply every year?
Not usually — once granted, the discount typically continues automatically as long as the qualifying conditions still apply, though the council may periodically review it, particularly if there's a change in the household's circumstances or the qualifying benefit is reassessed.
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