Council Tax Single Person Discount When Someone Has Dementia

How the SMI Disregard Creates a Single Person Discount

The single person discount is a 25% reduction for households with only one countable adult. Normally it applies when someone genuinely lives alone. But if two adults share a property and one qualifies for the severe mental impairment (SMI) disregard, that person is removed from the headcount — leaving one adult, which triggers the same 25% discount.

This is the most common outcome for couples where one partner has dementia. The partner with dementia is disregarded. The other partner becomes the sole counted adult. The discount applies automatically once the council approves the SMI claim.

When It Equals 100% — Living Alone with Dementia

If the person with dementia lives alone and qualifies for the SMI disregard, the result is not a single person discount at all — it is a Class U exemption. Every liable resident is disregarded, and the bill drops to zero.

This distinction matters because some councils mistakenly apply a 50% "all adults disregarded" discount instead of the full Class U exemption. If the only person living at the property is SMI-qualifying, the correct outcome is £0, not 50%. If your council has applied 50%, check whether Class U should apply — it often should.

The 25% Discount: Two People, One Disregarded

In a household of two adults — a couple, a parent and adult child, or any other combination — where one person meets both SMI conditions (medical certificate plus qualifying benefit), the disregard removes them from the count. One adult remains. The bill drops by 25%.

On a Band D property in England, 25% off the average bill saves roughly £500 per year. Over multiple years of backdating, that becomes significant.

The remaining adult does not need to be a carer. They do not need to claim anything. The 25% discount flows from the other person's SMI disregard, not from the remaining adult's circumstances.

Common Confusion with the Single Person Discount

People already receiving the standard single person discount sometimes worry that claiming SMI for a new resident will cancel it. It depends on who the new resident is.

If a person with dementia moves into a property where a single person already lives — say an elderly parent moving in with their adult child — the parent's SMI disregard means they do not count as an additional adult. The child keeps the 25% discount as if they were still alone.

If a non-qualifying person moves in (a partner without any impairment), the single person discount ends because two countable adults now live there. The SMI disregard does not help unless the new person also qualifies.

Backdating to When the Conditions Were First Met

The 25% discount (or Class U exemption) can be backdated. The effective start date is the latest of:

1. The date the person with dementia began living at the property
2. The clinical onset date of the severe impairment, as certified by the doctor
3. The start date of the qualifying benefit (Attendance Allowance, PIP daily living, etc.)

There is no statutory time limit on backdating. If the conditions were met three years ago and the claim is filed now, the council must recalculate all affected years and refund any overpayment.

Next Steps

If you are supporting someone with dementia who has not yet claimed the SMI disregard, the potential savings — especially with backdating — are worth checking. The two conditions are a GP certificate (free of charge) and a qualifying benefit.

Our SMI Council Tax Exemption Guide covers the full process, including household composition worksheets that show exactly what discount applies in your situation.

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