Part of: UK Council Tax 2026 — Complete Guide to Bands, Discounts, Exemptions & Appeals → Council Tax Exemptions — Every Class A to W Explained 2026
TL;DR: Class U exempts properties occupied solely by persons who are severely mentally impaired (SMI). To qualify as SMI, the person must have a severe impairment of intelligence and social functioning due to a condition that appears permanent, AND must be receiving one of the qualifying state benefits. Apply through your billing council with a GP certificate confirming SMI status and a benefit award letter. The exemption lasts indefinitely while the conditions persist.
Last reviewed: 27 April 2026
The Legal Basis for Class U
Class U of the Council Tax (Exempt Dwellings) Order 1992 provides a Council Tax exemption for properties occupied solely by persons who are "severely mentally impaired." The definition of severely mentally impaired (SMI) is also set out in the Order.
A related but distinct provision in the Council Tax (Discount Disregards) Order 1992 provides that a severely mentally impaired person is "disregarded" for Council Tax purposes regardless of what other people share the property. This means:
- Class U (exemption): All residents are SMI - 100% exemption, zero Council Tax.
- SMI disregard (discount): Some residents are SMI and some are not - the SMI residents are disregarded, and the non-SMI residents may qualify for the Single Person Discount if they are the only remaining counted adult.
Both provisions use the same SMI definition. The difference is whether all occupants are SMI (leading to Class U exemption) or only some are SMI (leading to the disregard provision).
The Local Government Finance Act 1992 provides the enabling power.
The Severely Mentally Impaired Definition: A Dual Test
The definition of "severely mentally impaired" requires TWO conditions to be met simultaneously - a medical condition requirement AND a qualifying benefit requirement.
Condition 1 - Medical: The person must have a severe impairment of intelligence and social functioning, however caused (whether by a condition that was congenital or acquired), that appears to be permanent, as a result of a condition such as:
- Alzheimer's disease or other forms of dementia
- Parkinson's disease (advanced, with significant cognitive impairment)
- Severe learning disabilities (for example, Down's syndrome at the more severe end)
- Severe stroke with significant cognitive and functional impairment
- Huntington's disease
- Multiple sclerosis (in advanced stages with cognitive involvement)
- Severe traumatic brain injury
The medical element requires certification by a registered medical practitioner (typically the person's GP or consultant).
Condition 2 - Qualifying benefit: The person must be entitled to (not necessarily receiving, but entitled to) one of the following benefits:
- Attendance Allowance
- Disability Living Allowance (DLA) - care component at middle or highest rate
- Personal Independence Payment (PIP) - daily living component at standard or enhanced rate
- Severe Disablement Allowance
- Incapacity Benefit (legacy benefit)
- Employment and Support Allowance (ESA) - support component
- Universal Credit with limited capability for work and work-related activity (LCWRA) element
- The disability element of Working Tax Credit
- Constant Attendance Allowance
The benefit does not need to be in payment - entitlement is sufficient. For example, a person who has not applied for PIP but would clearly qualify may still meet Condition 2 if they apply and are awarded entitlement.
Why Both Conditions Must Be Met
The dual test prevents Class U from being claimed for properties where a person has a qualifying benefit but is not genuinely severely mentally impaired, and vice versa. Both conditions must be satisfied for the exemption or disregard to apply.
In practice, the most common scenario is a person with advanced dementia who receives Attendance Allowance (the benefit most typically relevant to older people with dementia). A person with severe learning disabilities may receive DLA or PIP. A person with severe acquired brain injury may receive PIP at the enhanced rate.
The Under-Claim Problem
The IRRV and various disability awareness organisations have noted that the SMI exemption and disregard are significantly under-claimed. Estimates suggest that around 30% or more of households that could qualify for the SMI exemption or disregard are not claiming it.
Common reasons for under-claiming:
- Families and carers are unaware the exemption exists
- The dual test (medical + benefit) can be confusing
- GPs may not proactively advise patients to seek the exemption
- The application process requires proactive action at a stressful time (dementia diagnosis or brain injury)
- Billing councils do not always proactively identify eligible households
For a household with a severely mentally impaired person, the financial benefit can be substantial. If the SMI person lives alone, Class U gives 100% Council Tax exemption. If the SMI person lives with one non-SMI carer, the SMI disregard means the carer qualifies for the Single Person Discount (25% off). At the England average Band D, that is approximately £570/year.
The Application Process
Step 1 - GP or specialist certificate: The applicant (or their attorney, family member, or social worker) obtains a medical certificate from the SMI person's GP or consultant confirming:
- The person has a severe impairment of intelligence and social functioning
- The impairment appears permanent
- The qualifying condition (dementia, learning disability, stroke, etc.)
Step 2 - Benefit evidence: Obtain the current award letter for the qualifying benefit (DLA, PIP, Attendance Allowance, ESA, etc.).
Step 3 - Apply to the billing council: Most councils have an SMI exemption/disregard application form on their website. Submit the GP certificate, the benefit award letter, and any other requested documentation.
Step 4 - Revised bill: The council applies the exemption or disregard from the date the conditions are first met (typically the date of the GP certificate or the date the qualifying benefit was first awarded, whichever is later).
Applying When the Person Lacks Capacity
Many SMI individuals do not have the legal capacity to apply for the exemption themselves. In these cases, the application can be made by:
Attorney under a Lasting Power of Attorney (LPA): Where a property and financial LPA has been registered with the Office of the Public Guardian, the attorney can apply on behalf of the SMI person.
Court of Protection Deputy: A deputy appointed by the Court of Protection can act on behalf of the SMI person.
Appointee: Where the SMI person receives DWP benefits and an appointee has been appointed by DWP to manage their benefits, the appointee can typically assist with the application.
Family member or carer (with council's cooperation): In practice, billing councils often accept applications from family members or carers who can demonstrate they are acting on behalf of the SMI person, even without formal LPA or deputyship - particularly where the GP certificate clearly identifies the person and their incapacity.
The Practical Value of the SMI Exemption and Disregard: Financial Examples
To illustrate the financial impact of Class U and the SMI disregard:
Example 1 - Sole SMI resident (Class U - 100% exemption):
Mrs Chandra, 84, has advanced dementia and lives alone in a Band D property in a council with a Band D rate of £2,280. She receives Attendance Allowance at the higher rate. Her GP certifies severe mental impairment. Class U applies. Annual Council Tax saving: £2,280 (the full band charge - reduced to zero).
Example 2 - SMI resident with non-SMI carer (SMI disregard - 25% SPD):
Mr and Mrs Okonkwo. Mr Okonkwo has a severe learning disability (SMI-qualifying). Mrs Okonkwo provides care. Their Band C property has an annual charge of approximately £2,027. Mr Okonkwo is disregarded as SMI. Mrs Okonkwo is the sole non-disregarded adult. Single Person Discount (25%) applies. Annual charge: £2,027 × 0.75 = approximately £1,520. Annual saving: approximately £507.
These examples illustrate why the under-claim rate is financially significant - each eligible household that does not claim is paying money it should not be paying.
Class U vs the SMI Disregard
It is important to distinguish between:
Class U (exemption - 100% off): All residents at the property are severely mentally impaired. The property is fully exempt.
SMI disregard (partial relief): Some but not all residents are SMI. The SMI residents are disregarded, potentially reducing the number of counted adults and triggering the Single Person Discount or other adjustments.
Example: A household of a person with severe dementia (SMI) and their spouse (non-SMI) does not qualify for Class U because the spouse is not SMI. However, the person with dementia is disregarded, leaving the spouse as the sole non-disregarded adult. The spouse qualifies for the 25% Single Person Discount.
The Related Disabled Band Reduction Scheme
The Disabled Band Reduction Scheme (DBRS) is a separate provision under section 13 of the Local Government Finance Act 1992 and the Council Tax (Reductions for Disabilities) Regulations 1992. DBRS reduces the effective Council Tax band by one step for properties with qualifying adaptations for a disabled resident.
DBRS and Class U address different aspects of disability-related Council Tax relief:
- Class U (or SMI disregard): Based on the cognitive status of the resident.
- DBRS: Based on physical adaptations to the property (additional bathroom, wheelchair space, specialist room).
Both can potentially apply to the same property. A property with a severely mentally impaired sole resident (Class U exemption - zero Council Tax) would have Class U take precedence, making DBRS irrelevant during the exemption period. A property with an SMI person plus a non-SMI carer (SMI disregard applies but not Class U) may also qualify for DBRS if the property has relevant adaptations.
Frequently Asked Questions
My mother has advanced dementia and lives alone - does Class U definitely apply?
Yes, provided she meets both conditions: (1) a GP or specialist certifies she has a severe and permanent impairment of intelligence and social functioning due to dementia; and (2) she receives or is entitled to a qualifying benefit (Attendance Allowance is the most common for older people with dementia). Apply to the billing council with the GP certificate and the benefit award letter.
My father has dementia but lives with me (his daughter) - does Class U apply?
No. Class U requires all residents to be SMI. Since you (the daughter) are not SMI, Class U does not apply to the whole property. However, your father is individually disregarded under the SMI disregard provision in the Council Tax (Discount Disregards) Order 1992. You are the sole non-disregarded adult and qualify for the 25% Single Person Discount. At the England average Band D of approximately £2,280, this saves approximately £570/year.
Can I apply for the SMI exemption if my relative hasn't been formally diagnosed with dementia yet?
Class U and the SMI disregard require a GP or specialist certificate confirming the severe mental impairment. A formal diagnosis is not strictly required - the GP must certify the functional state (severe impairment of intelligence and social functioning appearing permanent) rather than a specific clinical diagnosis. However, in practice, GPs base the certificate on the clinical picture, which typically includes a diagnosis or assessment.
My brother has a severe learning disability (diagnosed at birth) - does the SMI disregard apply?
Yes, provided both conditions are met: (1) the learning disability produces a severe and apparently permanent impairment of intelligence and social functioning (the GP or specialist confirms this); and (2) your brother receives a qualifying benefit (DLA or PIP at qualifying rates). People with severe congenital learning disabilities frequently qualify for the SMI disregard.
Do I need to renew the SMI exemption each year?
Most billing councils do not require annual renewal for Class U or the SMI disregard, because the conditions (severe and apparently permanent mental impairment) are not expected to resolve. However, some councils do request periodic confirmation that the person's circumstances have not changed. The billing council will contact you if renewal is required.
How we verified this
Class U eligibility is from the Council Tax (Exempt Dwellings) Order 1992. The SMI definition and the qualifying benefit list are from the same Order. The SMI disregard is from the Council Tax (Discount Disregards) Order 1992. The Mental Capacity Act 2005 governs LPA and deputyship. DWP publishes guidance on qualifying benefits including Attendance Allowance, PIP, and DLA. MHCLG annual Council Tax statistics include Class U exemption volumes. The IRRV provides professional guidance on SMI application evidence standards. The under-claim estimate is from IRRV practitioner experience and Council Tax awareness campaigns.
Sources & Verification
- Council Tax (Exempt Dwellings) Order 1992 (Class U): https://www.legislation.gov.uk/uksi/1992/558/contents
- Council Tax (Discount Disregards) Order 1992 (SMI disregard): https://www.legislation.gov.uk/uksi/1992/548/contents
- Mental Capacity Act 2005: https://www.legislation.gov.uk/ukpga/2005/9/contents
- Local Government Finance Act 1992: https://www.legislation.gov.uk/ukpga/1992/14/contents
- DWP Attendance Allowance guidance: https://www.gov.uk/attendance-allowance
- DWP Personal Independence Payment guidance: https://www.gov.uk/pip
- MHCLG Council Tax guidance: https://www.gov.uk/government/collections/council-tax-statistics
- IRRV (Institute of Revenues, Rating and Valuation): https://www.irrv.net/
This article is for informational purposes only and does not constitute legal, financial, or tax advice. Council Tax rules vary by local authority and change annually. Always verify current rates and rules with your local council and gov.uk before making any decision.
