By Jo Piazza for Yahoo! Travel

Spirit raises fees yet again. (Photo: Thinkstock)

The budget airline Spirit already gets plenty of grief from passengers about their carry-on bag fees.

And yet, they are hiking up the fares yet again. The airline is raising their checked bag fees by $2 for flights in between Dec. 18 and Jan. 5 in an effort to encourage customers to “pack a bit lighter.”

Don’t even think about packing the presents. (Image: Spirit.com)

Spirit’s bag fees currently range from $20 to as much as $100 depending on when you book.

The Spirit business model is a bare-bones one. They start with an incredibly cheap fare and then charge customers for carry-ons, checked bags and in-flight snacks and drinks.

Related: Airfare Report—The Person Next to Me is Paying What?

The airline calls it the “bare fare.”

"Our fares are fully unbundled. No ‘free’ bag. No ‘free’ drink. Other airlines bake those options right into their ticket price. We don’t. A ticket with us gets you and a personal item from A to B," they explain on their website.

If you’re flying Spirit this year you might want to think about shipping those holiday presents sooner rather than later.