Passengers not booking tickets via Frontier Airlines’ website will start being charged this summer for overhead bin carry-on bags.

Additionally, for tickets booked on or after June 1 for travel on or after July 11, the carrier will raise its fee for a first check-in bag from $20 to $25 for economy passengers who don’t pay the bag fee on its website. The second checked-bag fee will remain $20 for all passengers.

Denver-based Frontier also this summer will introduce a $1.99 charge for onboard coffee, tea, soda and juice for passengers in economy seats, though some frequent flyer program members will be exempted. The drink fees, which will be payable by credit or debit card, will start July 1. Coffee refills will be free and passengers will receive full cans of soda or juice with their purchase.

The date for rolling out the carry-on bag fee, which will range from $25-$100, has not been specified. Passengers booking on the carrier’s website will still be allowed a free carry-on bag, and all passengers will be allowed a carry-on personal item, such as a laptop computer bag, that can fit under a seat.

Frontier said the moves are part of its effort to become an “ultra” low-cost carrier. It also cited passenger complaints about a lack of space in its overhead bins.

The carrier’s evolving model in part resembles Spirit Airlines’ pricing strategy. “Frontier continues to make it easier for customers flying with Frontier to pay only for the services they use, which allows us to continue lowering fares,” senior VP-commercial Daniel Shurz said.

The airline is also trying to direct customers to its website for transactions. Frontier is a subsidiary of Republic Airways Holdings, which has said it wants to sell or spin-off Frontier.