New federal regulations from the Transportation Department will require airlines to include all mandatory taxes and fees in advertised fares beginning Jan. 26.
Until now, the department has allowed airlines and travel agencies to list government-imposed fees separately.
Government-imposed fees can add 20 percent or more to the price of a ticket.
Southwest Airlines, Allegiant Air and Spirit Airlines have filed appeals to overturn the rule arguing that it violates commercial free speech rights.
Also starting January, airlines will be banned from increasing prices after a ticket has been purchased, and passengers will be allowed a 24-hour window to hold or cancel a reservation without penalty.