If you need to include a tourist tax as part of the total amount of your bookings, you can add a tourist tax by referring to this page (Accounts > Tax Rates).
Click on "add a tourist tax" and select the frequency in which this tax will be applied:
Bookinglayer will automatically add this tax to your booking's invoice:
IMPORTANT: Please note that this tax will be included in the total price of your products.
If you want to add a tourist tax as an additional amount, you will need to create this as an inventory item under "Services". Create a tourist tax service in your inventory and add it to your frontoffice options (Please refer to this article if you want to know more about how to create a service).