Part of: UK Council Tax 2026 — Complete Guide → Council Tax Disability Help 2026
TL;DR: The severely mentally impaired (SMI) Council Tax disregard is not limited to dementia. Severe schizophrenia, severe bipolar disorder with permanent cognitive impairment, severe autism with associated learning disabilities, and psychotic disorders with chronic effects can all qualify. The dual test applies: a GP or specialist certificate confirming severe and permanent impairment of intelligence and social functioning, plus a qualifying disability benefit.
Last reviewed: 27 April 2026
The SMI Definition Is Broader Than Dementia
The Council Tax (Discount Disregards) Order 1992, made under the Local Government Finance Act 1992, defines a severely mentally impaired person as one with "severe impairment of intelligence and social functioning, however caused, that appears to be permanent." The phrase "however caused" is crucial - the condition can be of any origin, including functional mental illness, neurodevelopmental conditions, or acquired brain injury.
Dementia is the most common SMI qualifying condition in practice (particularly among older residents), but the statutory definition covers a range of other mental health and neurodevelopmental conditions:
Severe schizophrenia: Chronic schizophrenia with persistent negative symptoms (poverty of thought, severe cognitive disorganisation, impaired social functioning) that has not remitted despite treatment. The clinical focus is on the permanence and severity of the resulting cognitive and social impairment, not the diagnosis label.
Severe bipolar disorder: Where bipolar disorder has resulted in permanent cognitive deficits - most commonly from repeated severe episodes, treatment effects, or associated conditions. Bipolar disorder that remits between episodes typically does not qualify. Bipolar with genuine permanent impairment of intelligence and social functioning can qualify.
Severe autism with associated intellectual disability: Autism with a significant intellectual disability (IQ under 70 or equivalent) meets the SMI test when the resulting impairment of intelligence and social functioning is severe and permanent. High-functioning autism (such as level 1 autism without intellectual disability) does not typically qualify.
Psychotic disorders with chronic impairment: Chronic schizoaffective disorder, persistent delusional disorder, or other psychotic conditions where permanent cognitive and social impairment results.
Severe traumatic brain injury: Permanent cognitive effects of brain injury qualify under "however caused" - a physical cause of mental impairment does not exclude the SMI definition.
Huntington's disease: A hereditary degenerative neurological condition with significant cognitive involvement in later stages. Qualifies as SMI as the cognitive effects progress.
What Does NOT Qualify
The "appears to be permanent" requirement is a meaningful threshold:
Moderate or mild depression: Clinical depression that may remit with treatment does not qualify as permanent. Even severe depression, if it is expected to respond to treatment and recover, does not typically meet the permanence test.
Treatment-resistant severe depression (exceptional cases): Where severe depression has been genuinely treatment-resistant over many years and the clinical picture suggests permanent impairment of intelligence and social functioning, the GP or specialist may be able to certify SMI. This is rare and requires a specific clinical assessment.
Anxiety disorders: Anxiety conditions, however debilitating, typically do not produce permanent severe impairment of intelligence and social functioning in the statutory sense.
ADHD/ADD: Attention deficit conditions without associated intellectual disability typically do not meet the SMI threshold.
The Dual Test: Certificate Plus Qualifying Benefit
As with all SMI claims, two conditions must be met simultaneously:
Condition 1 - Medical certificate: The person's GP or a specialist (typically a psychiatrist or neurologist) must certify that the person has a severe and apparently permanent impairment of intelligence and social functioning. For complex cases (severe schizophrenia, treatment-resistant bipolar), a consultant psychiatrist letter is often more persuasive than a GP certificate alone.
Condition 2 - Qualifying benefit: The person must be entitled to one of: PIP daily living component (either rate); DLA highest or middle rate care; Attendance Allowance (either rate); ESA support component; Universal Credit LCWRA element; Severe Disablement Allowance; Incapacity Benefit.
For mental health claimants, PIP daily living (standard or enhanced rate) and ESA support component are the most common qualifying benefits.
Class D vs SMI Disregard: MHA Detention
A separate distinction applies for people detained under the Mental Health Act 1983 or 2007:
Class D exemption: Provides 100% Council Tax exemption for a property whose sole resident is detained (in prison, under MHA, or under immigration detention). Class D exempts the property during the period of detention. Class D is not the same as the SMI disregard - it applies because the person is detained, not because of their clinical condition.
After MHA discharge: When a detained person returns home after discharge, Class D ends. If the person continues to have a severe and permanent mental impairment meeting the SMI test, the SMI disregard then applies. The two mechanisms operate sequentially for long-term mental health patients.
The Under-Claim Problem in Mental Health
Mind and Rethink Mental Illness have highlighted significant under-claiming of Council Tax SMI provisions among people with severe mental health conditions. The reasons include:
- Stigma: families and individuals are reluctant to declare a severe mental health diagnosis
- Complexity: navigating both the GP certificate and qualifying benefit requirements while managing a serious mental illness is difficult
- Lack of awareness: GPs do not routinely advise about the Council Tax SMI disregard
- Misunderstanding of the "permanent" test: families assume the person's condition will improve and therefore does not qualify
How to Support an Application for a Complex Mental Health Condition
For mental health conditions other than dementia, the GP certificate process can be more complex because GPs may be less familiar with the SMI Council Tax disregard in the context of functional psychiatric conditions. Some practical guidance:
Frame the certificate request correctly: The GP or psychiatrist needs to confirm two specific things for Council Tax purposes: (1) the person has a severe impairment of intelligence and social functioning, and (2) this impairment appears to be permanent. This is a clinical judgment call framed in statutory language. Providing the GP with the wording from the Council Tax (Discount Disregards) Order 1992 can help.
Use a consultant letter where possible: For severe schizophrenia or severe treatment-resistant bipolar disorder, a letter from the treating consultant psychiatrist confirming the severity and permanence of the cognitive and social impairment is more persuasive to the billing council than a GP certificate alone.
Include supporting evidence: Care records, support worker assessments, community mental health team correspondence, and PIP/ESA award letters all provide context. The billing council may review all of this in making their decision.
If the council refuses: An internal review and then an appeal to the Valuation Tribunal for England (in England) or equivalent in other nations is available. Provide the clinical evidence in full at the tribunal stage.
Backdating and Applying on Behalf of Someone Lacking Capacity
Backdating is available to the earliest date the conditions were both met. For mental health conditions with many years of chronic history, this can produce substantial refunds.
Where the person lacks capacity to apply themselves, the application can be made by:
- An attorney under a registered Lasting Power of Attorney (property and financial affairs)
- A Court of Protection deputy
- A family member or mental health social worker acting with the billing council's cooperation
Frequently Asked Questions
My son has severe schizophrenia and lives with us - does the SMI disregard apply?
It may. The key questions are: (1) does his schizophrenia produce a severe and apparently permanent impairment of intelligence and social functioning? and (2) does he receive a qualifying benefit? If the answer to both is yes, he is disregarded. Contact his GP or psychiatrist for a certificate and apply to the billing council.
The GP says my husband's bipolar is not "permanent" because treatment helps - does this block the claim?
The permanence test is about the underlying condition, not whether symptoms respond to treatment. If your husband has genuine, permanent baseline impairment of intelligence and social functioning even with treatment - for example, persistent cognitive deficits that do not remit - the GP may be able to certify that the condition appears permanent in that sense. Discuss the specific nature of the impairment with the GP.
My daughter was detained under the MHA - does she get Council Tax exemption?
During MHA detention, Class D exemption applies to her former home (if it is now empty). After discharge, if she returns home and continues to have a severe and permanent mental health impairment, the SMI disregard may apply. These are two different provisions operating at different times.
Mental health professionals say SMI means something different to them than for Council Tax - is that a problem?
Yes - the clinical term "severe mental illness" and the Council Tax statutory definition of "severely mentally impaired" are not identical. The Council Tax test focuses on severity of cognitive and social functioning impairment and its permanence. A clinical diagnosis of severe mental illness (such as schizophrenia) is strong supporting evidence but is not by itself the legal test. The GP or psychiatrist needs to certify the specific statutory elements.
Can I claim the SMI disregard and CTR at the same time?
Yes. The SMI disregard affects the household adult count (reducing it, potentially enabling SPD or Class U). Council Tax Reduction is means-tested relief applied to whatever charge remains after exemptions and discounts. Both can apply simultaneously to further reduce the bill.
How we verified this
The SMI definition (however caused, appears permanent) is from the Council Tax (Discount Disregards) Order 1992. Class D exemption (MHA detention) is from the Council Tax (Exempt Dwellings) Order 1992. The Mental Health Act 1983 and 2007 govern MHA detention. The Mental Capacity Act 2005 governs LPA and deputyship. DWP guidance covers qualifying benefits (PIP, ESA, UC LCWRA). Under-claim estimates are from Mind and Rethink Mental Illness published research. MHCLG guidance covers SMI disregard administration. The IRRV provides professional guidance to billing councils.
Sources & Verification
- Council Tax (Discount Disregards) Order 1992: https://www.legislation.gov.uk/uksi/1992/548/contents
- Council Tax (Exempt Dwellings) Order 1992 (Class D, Class U): https://www.legislation.gov.uk/uksi/1992/558/contents
- Mental Health Act 1983: https://www.legislation.gov.uk/ukpga/1983/20/contents
- Mental Capacity Act 2005: https://www.legislation.gov.uk/ukpga/2005/9/contents
- DWP PIP 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.
