It depends on the expert. Some experts offer a free five-minute or fifteen-minute intro session — no service fee, no VAT. It's a quick way to check whether an expert is the right fit before booking a full, paid session.
Whether an intro call is offered, and how long it is, is shown on the expert's profile.
Any session longer than the expert's free intro length is charged at the expert's rate plus the standard service fee and VAT. See "What fees does Tinrate charge?" for details.