Applying gift card to current reservation

[Abhinav23]

A friend of mine has made the reservation for our trip from their account. But now I have an Airbnb gift coupon, can the coupon be redeemed by my friend on the current booking?

[Emiel1]

@Abhinav23 

A coupon must be used personally and can be applied at check-out (payment) when making a reservation.

https://www.airbnb.com/help/article/160/how-do-coupons-work