If you collect rent from them or accept any other form of compensation in lieu of rent (such as paying your HOA fees or cleaning fees), you are required to collect and remit the Tourist Development Tax. This tax is based on the rent plus any additional fees paid or the fair market value of the compensation received. For example, if a friend stays in your condo unit and pays your HOA fees during their stay, this is considered a taxable transaction.
If you do not receive or expect any compensation (including cleaning fees or any other required, non-refundable fees) from your friends or relatives, ensure you document this in your records in case of an audit.