Annexe Council Tax: Bands, the 50% Discount and Exemptions

Annexe council tax catches many households by surprise: build or convert a granny annexe and you can end up with two council tax bills for one property. The rules cut both ways, though. The law forces a separate band onto any self-contained annexe, but England also offers a 50% reduction on the annexe's bill in common family situations, and a full exemption where a dependent relative lives in it. This guide explains when an annexe gets its own band, how to claim the reliefs, and what to do if your annexe was banded when it should not have been.

Does a granny annexe pay council tax?

Yes, if it is self-contained. The gov.uk assessment guidance is explicit: any building, or part of a building, that has been constructed or adapted for use as separate living accommodation must have its own council tax band. That applies whether the annexe is a converted garage, a room over the garage, a basement flat, or a purpose-built garden building. It also applies even when the annexe is empty: as long as it could be occupied separately, the separate band stays. What you actually pay on that band then depends on who uses the annexe, which is where the 50% reduction and the Class W exemption come in.

When does an annexe get its own council tax band?

An annexe is banded separately when it is self-contained, meaning it works as a home in its own right. The VOA looks at the physical features, not what you call the space or how you happen to use it. The features that matter are:

• Independent access: its own entrance, or access from a hallway, landing or other common area rather than through the main home's living rooms.
• Sleeping space: somewhere to sleep that is separate from the main accommodation.
• Cooking facilities: its own space for preparing food.
• Washing facilities and a toilet: a bathroom or shower room of its own.

Once an annexe passes that test, one of three outcomes applies to the bill in England:

How do I get the 50% annexe discount?

You apply to your council, and you qualify through one of two routes set out in the Council Tax (Reductions for Annexes) (England) Regulations 2013, which have applied since 1 April 2014: either the annexe is the sole or main residence of a relative of the person liable for council tax on the main home, or a resident of the main home uses the annexe as part of their own sole or main residence (a home office, guest space or teenager's den, for example). "Relative" is defined broadly, covering spouses, civil partners, parents, children, grandparents, grandchildren, siblings, aunts, uncles, nieces and nephews, including step-relations and in-laws, and there is no age or disability condition for this reduction. To claim it:

1. Confirm the annexe has its own band. Check the address on the official list; if it has no separate band, there is no separate bill to reduce.
2. Identify your route: a relative living there, or use of the annexe as part of the main household's residence.
3. Apply to your council, not the VOA. The billing authority administers the reduction; most councils have an annexe discount form on their website.
4. Set out who lives in or uses the annexe and their relationship to the person named on the main home's bill.

Is an annexe exempt if a relative lives in it?

Only if they count as a dependent relative. Class W of the Council Tax (Exempt Dwellings) Order 1992 exempts a dwelling that forms part of a single property with at least one other dwelling, where it is the sole or main residence of a dependent relative of someone living in the other dwelling. A relative is dependent if they are aged 65 or over, severely mentally impaired, or substantially and permanently disabled. Meet the test and the annexe pays no council tax at all, which is why it is worth checking before settling for the 50% reduction. A younger, able relative gets the 50% reduction instead. The order applies to England; Wales runs its own version, so Welsh households should confirm the position with their council.

Why annexes are the exception to the improvements rule

Normally, home improvements cannot raise your council tax band until the property is next sold: the VOA adds an improvement indicator and waits for the sale before reassessing, as our extensions guide explains. Annexes are the exception. The VOA's own guidance from 13 July 2023 confirms that when self-contained living accommodation is created, it can review the position straight away, without waiting for a sale, because a new dwelling has come into existence rather than an existing one being improved. In practice that means a newly built or converted annexe is banded as soon as the VOA learns of it, often after a planning or building control record, and the household starts receiving a second bill.

What if my annexe should not have its own band?

If the space does not genuinely pass the self-contained test, or no longer does, ask the VOA to remove the band. Two situations are common. First, the original decision was wrong: the "annexe" lacks its own cooking or washing facilities, or can only be reached through the main home's living space, so it was never separate living accommodation. Second, you have converted it back: the gov.uk guidance says the VOA will delete a band where the area has been sufficiently altered that it could no longer be lived in separately. The bar is physical and real. Removing a sink or a cooker on its own, with no other works, will not persuade the VOA that the separate accommodation has gone.

Can I appeal my annexe's band?

Yes. An annexe band is challenged the same way as any other: free of charge through the VOA's official process, and you never need to pay anyone to submit it. There are two distinct arguments. If the annexe should not be banded at all, present the self-contained test evidence described above. If the band is simply too high, you need comparable evidence: what similar small self-contained units nearby are banded at, and what the annexe would have been worth on 1 April 1991. Be honest with yourself about the risk in both directions, because a review can move a band up as well as down. Our step-by-step challenge guide covers the process, and Council Tax Challenger's £9.99 evidence pack does the comparable research for your postcode so you can see whether the case is worth making before you contact the VOA. The reliefs, meanwhile, come from the council rather than the VOA, so if a relative lives in your annexe, claim the 50% reduction or Class W exemption whatever the band says. Our discounts and exemptions guide lists what else you may qualify for.