When do you pay the Las Vegas resort fee: at booking or at check-in?

At the hotel, almost always. The booking site takes the room rate or a deposit; the resort fee is collected by the property when you arrive.

At check-in the desk authorizes your card for the room, the tax, the resort fee for every night of the stay and a daily incidentals hold. The fee then settles on your final folio as one line per night.

Prepaid through a third-party site? Same thing. Unless the site clearly says the resort fee is already inside your total (a few package deals do this), the hotel still collects it on arrival. What changed in May 2025 is the FTC junk-fee rule: the all-in price with the fee has to be shown before you pay, so the amount should no longer surprise you, only the timing.

Split stays across two hotels pay each hotel's fee for its own nights; nothing doubles up.

The incidentals hold is not a charge. It drops off a few days after checkout, but on a debit card it ties up real money, which is why we hand over a credit card at the desk.

What the fee buys and the three ways around it are in resort fees explained; the amount at each hotel is in resort fees by hotel.