The deposit, which is only ever the first half
A deposit here is the first half of the fee rather than money set aside, named as a figure in the thread once the hour is agreed and paid before she leaves.
The word usually suggests a sum held back and returned later. That is not what happens here. The deposit is the first half of the fee itself, calculated from the figure printed in the profile of the therapist you asked for, and once it is settled the amount still owed is exactly the other half.
Which bookings ask for it
Seven kinds: anything fixed more than twenty-four hours ahead, an eight hour night, two therapists in the room, a room at Schiphol or an airport hotel, a busy date in the city calendar, three hours or longer, and any guest’s first booking. One booking asks for nothing in advance, which is a returning guest wanting an hour or two later the same day at an address inside the city. The full reasoning, with figures worked through, sits on the deposit and notice page.
How it is settled
Card is the ordinary route, with Revolut, Wise and cryptocurrency available to anyone who would rather not use one. There is no bank transfer route here and no PayPal route either. Cash cannot serve, because the first half is settled before she leaves and cash only moves once she is in the room. The amount and the destination appear in the booking thread after the hour is agreed, and in no other place.
Why it exists at all
An hour agreed is an hour taken off her evening, along with the awkward stretch on either side of it. Half ahead makes the promise mutual: you know the hour is genuinely held, and she knows the journey out is not being made on a guess. What happens to that half if plans change is set out under cancellation and refunds, and moving the date instead is covered under rescheduling.