Earlier this year, the airline announced plans to end its trademark “bags fly free” policy to help shore up earnings.

Southwest Airlines has updated its checked bag policy, and passengers will start paying extra tomorrow. Southwest has long allowed passengers to bring a guaranteed free checked bag, but that is changing tomorrow as the airline adopts a new policy.

For Southwest flights booked on or after May 28, it will cost $35 to check a bag — unless you buy the most expensive fare or have loyalty status.

Next week the carrier plans to kick off a new policy that will make flying more expensive for many of its customers.