taxquestion

We have a second home (personally owned) that doesn't qualify for Furnished Holiday Let and is mainly used for renting out via AIRBNB on short term basis. We also use it for weekends occasionally and the rest of the time will be vacant but constantly marketed for rent. My understanding is that in this case can pro-rata the various expenses/bills based on the time used by paying guests. So if the property is rented for say 60 days a year, we use it 15 days and rest of the time is vacant. My question is the calculation for pro-rata costs 60/75 or 60/365 or no pro-rata required at all and can claim full expenses. Linked to this if any repair work is done which from reading would qualify do we have to pro-rata that all?