We renovated an tiny old cottage at the back of our house recently to a one-bedroomed house. It shares electric supply with us but has it own other services. It is in a very touristy location where most houses are holiday homes. We have used it only for family and friends last year. We had thought we would possibly do airbnb this year but now a young local couple has asked to rent it from us. Also, how should we adjust our LPT or should it be registered as a new house. We did not get any planning as we were advised it was not necessary as a "renovation". Would we have to register with RTB and what are the long-term implications of that.