If you've ever flown Spirit Airlines, you are familiar with the "pay for what you use" model: low base fares, with additional fees for everything else. Thankfully for active duty military folks, Spirit Airlines has amended their policies to allow active duty military members one free carry-on and two free checked bags. In addition, service members who have already paid for bags will be issued refunds at the ticket counter.
This change was effective on 19 February 2016. My husband happened to fly Spirit Air that day (total coincidence) and he had already booked one carry-on and one checked bag. We were completely unaware of the change, so he was really surprised when he got to the counter and was informed that Spirit Air would be refunding the $60 in baggage fees that he had already paid. He said they were really nice about it and the credit showed upon our credit card bill immediately. I feel like this was great service on their part.
Baggage costs on Spirit airlines vary dramatically depending on the flight and when you pay for the baggage, with lower prices for pre-booking luggage and higher prices for ticket counter checking and gate checking. Depending on your flight and situation, you could potentially save up to $300 with this new policy. (No, I can't imagine anyone suddenly turning up at the gate with three pieces of surprise luggage, but you never know. I have seen stranger things.)
Not only is this a great benefit to members who need to bring luggage because uniforms take up a lot of space, it is a generous courtesy for those travelling for pleasure.
It appears that there is no way to show that you're bringing bags online without paying for them, so I guess you are just supposed to show up at the airport with your luggage and show your military ID. However, I would advise trying to call them to verify this information before making a booking. Since this policy is new, I suspect there will be some tweaks and adjustments as they get used to the new rules. Who knows what the rules might be in a week or a month.