50 Percent Council Tax Discount on Annexes: The Family Annexe Reduction

What the 50% Annexe Reduction Is

The Council Tax (Reductions for Annexes) (England) Regulations 2013 introduced a mandatory 50% council tax reduction for qualifying annexes. It took effect on 1 April 2014 and applies across every billing authority in England.

Before this legislation, families with separately banded annexes paid the full council tax on both the main house and the annexe — even when the annexe was used by a family member or treated as part of the main home. The 50% reduction fixed that by recognising that a family annexe is fundamentally different from an independent rental property.

Two Ways to Qualify

The regulations set out two alternative eligibility routes:

Route 1: Used as part of the main home. The annexe forms part of a single property containing another dwelling, and a resident of the main dwelling uses the annexe as part of their sole or main residence. This covers spaces used as a home office, gym, studio, playroom, or extra family living room — any genuine extension of main-home living, even if the space has its own kitchen and bathroom.

Route 2: Occupied by a relative. The annexe is the sole or main residence of a relative of the person liable for council tax on the main dwelling. Unlike Class W (which requires the relative to be aged 65+, severely mentally impaired, or disabled), the 50% reduction has no dependency requirement. An adult child, a sibling, a cousin, or a non-dependent parent qualifies.

How the Reduction Is Calculated

The 50% annexe reduction does not simply halve the base bill. Personal discounts under Section 11 of the Local Government Finance Act 1992 are applied first, and the 50% reduction is then calculated on the remaining balance.

Take a Band C annexe with a base annual bill of £2,000. If a single adult lives there alone, the 25% single person discount knocks the bill down to £1,500. The 50% annexe reduction then halves that to £750. The effective combined saving is 62.5%.

If two adults live in the annexe, there is no single person discount. The 50% reduction halves the full £2,000 to £1,000.

What the 50% Reduction Does Not Cover

The relative-occupation route does not apply to a non-relative tenant, lodger, or friend. The separate main-home-use route may still qualify if a resident of the main dwelling uses the annexe as part of their sole or main residence. Empty investment annexes without that use or a qualifying relative do not qualify.

For this reduction, qualifying relatives include a spouse, civil partner, parent, child, grandparent, grandchild, sibling, uncle, aunt, nephew, niece, their great- and great-great-equivalents, and cousins; relationships through marriage, civil partnership, and step-relationships count.

How It Interacts With Class W

If the annexe qualifies for both Class W (100% exemption for a dependent relative) and the 50% reduction, Class W takes priority because it wipes the bill entirely. The 50% reduction is the fallback — it catches the scenarios where Class W fails, most commonly because the occupant does not meet a dependency test. Another adult living in the annexe does not, by itself, defeat Class W.

How to Claim

Apply to your local billing authority. You will typically need to provide evidence of the family relationship and confirm that the annexe is either used as part of the main home or occupied by a qualifying relative.

Our Annexe Discounts and Exemptions Guide includes the full decision flowchart for working out which relief applies to your situation, along with the evidence and application steps for each route.

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