If the value of the voucher is equal to or greater than the base fare of the ticket,the following taxes are not charged: 7.5% Federal tax,$3.20 segment tax,and the $2.50 security tax. The only collectable tax is the airport tax of $3.00 or $4.50.
If the value of the voucher is less than the the base fare of the ticket the only tax savings is the 7.5% federal tax on the value of the voucher.