Southwest Airlines will end its iconic “Bags Fly Free” policy on May 28 and introduce checked bag fees for the first time in the carrier’s history.

Most passengers will pay $35 for their first checked bag and $45 for the second bag.

The policy shift marks the end of an era for the Dallas-based airline, which has long distinguished itself from competitors by allowing passengers to check bags without additional fees.

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CEO Bob Jordan said the changes, which the company announced in March, are part of an effort “to meet current and future customer needs” and “attract new customer segments we don’t compete for today,” Fox Business reported. The airline faces mounting profit pressures as it seeks to boost revenue.

Tuesday marks the last opportunity for travelers to book flights under the old policy. The new fees will only apply to flights booked or changed on or after May 28.

Southwest is simultaneously introducing a basic fare option and assigned seating. The assigned seating represents another departure from Southwest’s traditional open seating model.

The new charges will be waived for some travelers. Premium passengers and those with qualifying loyalty status will continue receiving free checked bags.

The baggage fee puts Southwest in line with most major U.S. carriers. Airlines have increasingly relied on ancillary revenue streams to improve profitability in a competitive market.

Southwest has published additional details about the policy changes on its website and updated its travel baggage guidelines.