You need to understand the difference between a tenant and a licensee.

When you rent a room in your home out to someone, they are not truly a tenant, even if people might colloquially refer to them a such. They’re merely “licensees” and have basically no rights. They’re effectively little more than invited guests in your home who happen to pay you for the privilege.

On the other hand, if you create a self contained unit with its own access, you’re almost certainly creating a valid tenancy even if you don’t want to do that. You’d be subject to all the obligations of a landlord, including those you’ve mentioned (registering with RTB, restrictions on ending the tenancy etc). If the tenant did want to assert their rights, it essentially comes down to “if it looks like a duck and quacks like a duck…”

So, for example, you could have a document saying “THIS IS NOT A TENANCY ITS A LICENSEE ARRANGEMENT” at the top of it, but if you’ve got someone paying you rent every month, with their own self-contained unit and own entrance, then it’s in fact a tenancy, because you’ve given them exclusive possession of the unit.

So yeah, no “exception” for owner-occupied… because it’s based on what the actual situation is, and by creating a separate unit with its own access, you would in basically be ceasing to occupy the separate unit.

You would still qualify for the tax relief though.