Denver-based Frontier Airlines is the latest carrier to charge extra for carry-on bags that require overhead storage—joining other add-on fees for non-alcoholic drinks ($1.99) and seat assignments (up to $8). In exchange, the airline is lowering its ticket prices by 12%.

It’s a business model long used by other ultra low-cost airlines such as Spirit, which began charging for carry-ons in 2010. (This change should come as no surprise, seeing that Barry L. Biffle, Frontier’s new president, was a Spirit executive for nine years.) As of April 28, Frontier passengers will pay $25 for a carry-on at the time of booking online, $35 at the airport, and $50 at the departure gate. (Bags that can fit under the seat remain free.) Elite status frequent fliers and those who purchase the more expensive, fully refundable Classic Plus fares will receive extra legroom, a free checked bag, and a free carry-on.

Brooke Porter Katz is an Associate Editor at Travel + Leisure. Follow her on Twitter at @brookeporter1.