HMRC’s internal manuals provide the following example:
Imagine a person registered as a self-employed plumber who now and again renovates old cars. They do not automatically have to charge tax when selling those cars. This is because it would be hard to see the activity of car renovation being included within their business as a plumber.
On the other hand, if the car activity can be seen to have the attributes of a business in its own right then the plumber would have to charge tax on the sales.
Source: lawtonbradford.com
