How Much Council Tax Discount for SMI?

The Short Answer: It Depends on the Household

The SMI disregard does not give a fixed pound amount or a single percentage. It removes the qualifying person from the council tax headcount. The discount you actually receive depends on how many other adults live in the property after the disregard is applied.

The Three Possible Outcomes

100% reduction (Class U exemption — £0 bill). This applies when the SMI person lives alone, or when the dwelling is occupied only by one or more SMI people and any other occupants fall within the categories allowed under Class U (such as full-time students). The property is exempt from council tax entirely. The 2026/27 England average Band D bill is £2,392, so the exemption removes roughly that amount of annual liability.

25% reduction (single person discount). This applies when the SMI person lives with one other non-disregarded adult — most commonly a spouse or adult child. The household drops from two counted adults to one. On the 2026/27 England average Band D bill of £2,392, the annual saving is roughly £598.

0% reduction. This applies when the SMI person lives with two or more other non-disregarded adults. The disregard still protects the SMI person from personal liability, but the household headcount stays at two or more and no occupancy discount kicks in.

How the Numbers Stack in Real Terms

Council tax bills vary substantially across England. The 2026/27 England average Band D amount is £2,392, but local rates differ. Here is how the SMI discount plays out at different band levels:

For a person living alone with SMI (Class U exemption), the saving is the entire bill — whatever their band charges. For a couple where one person has SMI (25% discount), the saving is a quarter of the bill. On a Band B property charging £1,600, that is £400 per year. On a Band F property charging £2,800, that is £700 per year.

Stacking With the Disabled Band Reduction

If the property also qualifies for a disabled band reduction — because it has been structurally adapted with an extra bathroom, a room used for therapy, or space for a wheelchair — the band is dropped by one level before the occupancy discount is calculated. A Band D property drops to Band C billing rates, then the 25% or 100% reduction applies to the lower amount.

These two reliefs operate independently. The disabled band reduction is a property-based relief assessed by the council, while the SMI disregard is a person-based relief. Qualifying for one does not affect eligibility for the other.

The Backdating Multiplier

The value of the SMI discount compounds when backdated. At the 2026/27 England average Band D amount, a 25% discount worth about £598 per year becomes about £2,990 over five years. A Class U exemption worth £2,392 per year becomes £11,960 over five years. These are real refunds that the council must pay once a backdated claim is approved.

Because council tax liability is calculated daily under the LGFA 1992 and no statutory time limit on backdating exists in the primary legislation, the refund can reach back as far as the evidence supports — often to the date the qualifying benefit was first awarded or the GP's certified onset date, whichever came later.

Council Tax Reduction Is Separate

The SMI disregard is not means-tested. It applies regardless of income, savings, or property value. Council Tax Reduction (CTR), which is the means-tested scheme administered by each local authority, is a completely separate mechanism. A household can receive both the SMI disregard and CTR. The SMI discount is applied first, then any CTR reduction is calculated against the remaining liability.

For the household composition worksheet and backdating calculation tools, see our Severe Mental Impairment Council Tax Exemption Guide.

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