You can access your Taxes tab by clicking on your property name and then Property settings. To edit Value Added Tax (VAT) settings, select Yes to Property is VAT registered.
Additional options will open up:
VAT is included in my rates - select Yes if you want the price shown in invoices issued through Rentlio to include VAT; if you want to add VAT on top of the price entered in Rentlio and synced to online reservation channels, select No
Accommodation VAT rate - enter the VAT rate that applies to accommodation services
After you enter your settings, click on Save.
In case you need to add some other taxes, you can read here how to do it.