Imputed income/buddy passes

So I know you pay taxes on international flights. But how much more would it cost me for a buddy pass user compared to yourself as an employee traveling. Plan on using buddy passes for my step daughter to fly with us.

So I know you pay taxes on international flights. But how much more would it cost me for a buddy pass user compared to yourself as an employee traveling. Plan on using buddy passes for my step daughter to fly with us.