If you're registered for tax, turn it on in Settings, under Money and tax. Bookables shows the tax on your invoices and receipts, with your registration number. It's prefilled for your country, so check the rate and number before you save.
Open Settings, then Money and tax
Find Tax.
Switch on Charge
The switch is named for your country's tax, like Charge VAT.
Check the details
Name is what invoices call it, like VAT. Rate is your standard rate as a percentage. Under Your prices, choose Include it if your prices already include tax, or Have it added on top.
Add your registration number
It's printed on every invoice.
Choose Save tax
Tax applies to bookings made from now on.
A booking keeps the tax it was made with. Turning tax on, off or changing the rate applies to bookings made from now on. Bookings already made stay as they were.
Switch off Charge and choose Save tax. Prices are shown without tax on bookings made from then on.
Bookables shows tax on your invoices and receipts. It doesn't decide whether you must register, and it doesn't file returns.
Your currency follows your country, and every booking is in it. Both show at the top of Money and tax. Choose Change country if they're wrong.