Deposit: the first half, paid before she travels
A deposit is half of the price, paid before she sets out. It is not an extra charge. The other half, the balance, is paid when she arrives.
A deposit is part of the price, paid early. On this site it is always one half. For one hour at 180 euros, the deposit is 90 and the balance is 90. For the overnight at 1,250 euros, it is 625 and 625.
When there is a deposit
Most bookings have one. There is a deposit when you book more than twenty-four hours ahead, when you book the overnight, two therapists, three hours or more, an address at Schiphol or an airport hotel, a busy date such as King's Day, or your first booking with the house. Just one kind of booking skips it: a guest who has booked before, asking for one or two hours later the same day at an address in the city.
How it is paid
By card, or by Revolut, Wise or crypto. It is never paid in cash, because cash can only be paid in the room, and the deposit comes before she leaves. The figure and the payment details come in the booking thread, after the hour is agreed.
If you cancel
What happens to the deposit depends on your notice. The entry on cancellation and refunds gives the three steps, and the booking terms give worked examples in euros.