The TUI fly gift voucher is only valid if you book directly through TUI fly.
In step 3 of the booking process you should enter the number of the gift voucher as well as its activation code. The system will then automatically check the validity of the voucher.
This gift voucher can be used as (partial) payment for one or more flight tickets offered by TUI fly. For each flight reservation multiple gift vouchers can be used. However, the value of the Gift Voucher cannot be deducted from the price of a trip that has already been taken or booked.
As soon as the TUI fly Gift Voucher is used as (partial) payment of a TUI fly booking, it is no longer valid. The TUI fly Gift Voucher cannot be converted into cash and cannot be exchanged for another TUI fly Gift Voucher for the amount mentioned or for part of this amount.