My elderly mother lives in the annexe rent-free — does the discount apply?

Yes. There is no requirement that rent be paid or not paid. The discount depends on the family relationship and the physical status of the annexe, not on commercial arrangements.

We converted the garage into a flat for my son — does that count as an annexe?

It can, provided: (a) the conversion is self-contained with its own entrance, kitchen, or bathroom; (b) the VOA has separately banded it; and (c) your son qualifies as a 'relative' under SI 2013/2977 (which as your child, he does). If the VOA has not separately assessed it, contact them.

Can I get the discount backdated if I did not know about it?

Yes. Request retrospective application from the date the qualifying conditions were first met. There is no statutory time limit. The council must refund any overpaid council tax for the backdated period.

Paying Full Council Tax on a Granny Annexe

By GetRighted Legal Research TeamLast updated July 2026

Summary

If a family member lives in an annexe attached to your main home, you are almost certainly entitled to a 50% council tax discount on the annexe — and you may be paying hundreds of pounds more than you should. The Council Tax (Reductions for Annexes) (England) Regulations 2013 (SI 2013/2977) make this discount mandatory where the occupant is a relative of the main dwelling's liable person. Many households do not know this discount exists, and billing authorities rarely apply it proactively.

Qualifying for the Annexe Discount

Three conditions must all be met: (1) the annexe is part of a single property with the main dwelling — same land title or physically attached; (2) the annexe is separately assessed for council tax by the Valuation Office Agency (it has its own council tax band); (3) the occupant is a 'relative' as defined in SI 2013/2977 — parent, child, grandparent, grandchild, sibling, uncle, aunt, nephew, niece, or the spouse or civil partner of any of these. If all three are satisfied, the discount is mandatory.

Full Exemption May Also Be Available

If the annexe occupant is aged 65 or over, substantially and permanently disabled, or has Severe Mental Impairment, the annexe may qualify for full exemption under SI 1992/558 Class W — not just the 50% discount. Class W is often overlooked. Check eligibility before settling for the 50% discount.

Documents for Your Claim

Provide these to the billing authority:

VOA council tax reference number for the annexe showing it is separately banded
Land registry title or planning permission showing the annexe and main dwelling form part of one property
Proof of the family relationship: birth certificate, marriage certificate, or statutory declaration
If claiming Class W exemption: evidence the occupant is 65+, permanently disabled, or has SMI

What If the Annexe Is Not Separately Banded

If the VOA has not separately assessed the annexe — perhaps because it was converted without formal planning — the annexe may be included within the main dwelling's council tax band. In that case, the separate annexe discount does not apply, but you may be paying too much if the combined band is too high. Contact the VOA to request a review. If they separately band the annexe, the 50% discount becomes available.

Sources

Council Tax (Reductions for Annexes) (England) Regulations 2013, SI 2013/2977
Council Tax (Exempt Dwellings) Order 1992, SI 1992/558, Class W

Frequently Asked Questions

My elderly mother lives in the annexe rent-free — does the discount apply?: Yes. There is no requirement that rent be paid or not paid. The discount depends on the family relationship and the physical status of the annexe, not on commercial arrangements.
We converted the garage into a flat for my son — does that count as an annexe?: It can, provided: (a) the conversion is self-contained with its own entrance, kitchen, or bathroom; (b) the VOA has separately banded it; and (c) your son qualifies as a 'relative' under SI 2013/2977 (which as your child, he does). If the VOA has not separately assessed it, contact them.
Can I get the discount backdated if I did not know about it?: Yes. Request retrospective application from the date the qualifying conditions were first met. There is no statutory time limit. The council must refund any overpaid council tax for the backdated period.

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