Granny annexes

Many families want an older parent to live close by.

An annexe in the garden, or a part of the house set up as a separate home, can give a parent their own front door a few steps away. Building one raises questions about planning, building work and council tax.

These notes follow the rules in England. Wales, Scotland and Northern Ireland have their own.

Planning permission

Householders can put up many garden buildings without planning permission. These "permitted development" rights cover sheds, garages and similar buildings used alongside the home. The Planning Portal explains that they do not cover a building used as separate, self-contained living accommodation.

The rules are tighter for listed buildings and in conservation areas and National Parks. Your local planning authority can tell you what applies to your home. It can also grant a lawful development certificate, which confirms that a proposed use or building would be lawful.

Building regulations

Building regulations approval is a separate thing from planning permission, and a project may need both. The Building Regulations 2010 cover the construction and extension of buildings. Putting in a bathroom with plumbing is one of the jobs that can need approval.

Approval can come from the council's building control team or from a private registered building control approver. Without it, the owner may be missing the certificates they need when they come to sell the home.

Council tax bands

The Valuation Office decides whether part of a property counts as separate living accommodation. It looks at physical features such as a separate entrance, a kitchen, and a shower and toilet. An annexe with these would normally get its own council tax band.

The Valuation Office looks only at the building, not at who lives in it. A self-contained annexe keeps its band even while it stands empty.

Council tax discounts for family annexes

Since April 2014, councils in England have taken 50% off the council tax on an annexe in two cases. One is when the annexe is the main home of a relative of the person paying council tax on the main house. The other is when the household in the main house uses the annexe as part of its own home.

An annexe can be exempt altogether when it is the main home of a dependent relative. The law counts a relative as dependent if they are aged 65 or over, severely mentally impaired, or substantially and permanently disabled. Your council decides each case, so ask them.

Talking it through as a family

Age UK suggests that families agree a few things before anyone moves.

Putting money into a relative's home can affect a later assessment for care home fees. Age UK suggests independent legal advice and a written agreement.

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