When is the buyer actually charged?

Nothing is charged when a buyer taps Buy. The card is authorized — the money is held, not taken — and the item is locked to that buyer.

The charge happens at the end, once the item has changed hands. The buyer taps Accept and the money is released to the seller and to any causes on the listing. Where the handoff was photographed, the sale also completes on its own if the buyer says nothing for 24 hours.

The seller's confirmation does not move money. Only the buyer's acceptance, or that automatic completion after a photographed handoff, does.

If the deal does not happen, the authorization is cancelled and the buyer is never charged at all. A hold that expires, a confirmed no-show and a dispute decided for the buyer all end that way — by releasing money that was never taken.

Once a sale is complete there is no in-app reversal. Everything that undoes a deal works before the money is taken, not after.