Planning Issues for Self Contained Annexes

A self-contained annex is a popular reason for building an extension. Building one can give teenagers and young adults a chance to live independently but have the security of being close to home.

The same benefits apply to annexes that provide accommodation for elderly or disabled relatives. Or sometimes they are built to provide accommodation for live-in nannies, au pairs or long-term guests.

Take Care When Planning an Annex

But there are a few things you have to be careful about when planning a self-contained annex to make sure that it’s not treated as a separate dwelling. It’s a confusing area and much of the advice is contradictory. You will need to take advice about your specific property and plans.

There are two main issues, council tax and planning. The planners will take into account the use the extension is to be put to when deciding whether or not the annex should be treated as a separate property. But the council won’t, they will base their decision purely on the construction of the extension.

So here we’ll try and make sense of some of the guidelines, but we must emphasise the importance of getting advice from the planners and the council before embarking on the building of the extension. Let’s take the council first.

Council Approach to Self-Contained Annexes

The council will be assessing whether or not they should be charging your annex for council tax as through it were a separate property. To do this they will look at the physical layout of the extension, the access and the facilities.

If the accommodation is all in one area, not split around different areas of the original property, they would not treat it as a separate property. But then that would be useless as a self-contained annex so it’s not really a solution. If the annex has a complete set of equipment for living (cooking and bathing facilities as well as living and sleeping) then the council are more likely to treat it as a separate property. So that would include most annexes.

Access to self-contained annexes used to be an important factor but most councils are down-playing it now. Many council websites state that an annex does not have to have its own entrance to be considered self-contained for the purposes of council tax. In the past people would keep an access door into the house from the annex to prevent it from being treated as a separate property but that would no longer seem to apply.

Planning Position on Annexes

From the planning point of view the approach is slightly different and has changed recently, so again it’s wise to get up-to-date advice. Usage is taken into account as to whether planning permission is required.

For example an extension providing an annexe for an elderly relative who makes frequent use of the lounge in the main property would not require planning permission. On the other hand, the very same extension, if rented out to an eighteen-year-old student who was not related and had their own car, would.

Use the Right Words When Planning

If you do need to apply for planning permission for the annex, not because it’s an annex but because it’s a particular size, or because of the rules in your area, then you can describe it as an extension in all the documentation. Avoiding the word ‘annex’ in your planning documentation won’t necessarily stop the council assessing it as a separate property but calling it one almost certainly will.