NEW YORK (CNNMoney.com) - Last-minute fliers are getting shut out before they reach their departure gate as airports step up their enforcement of stated check-in times, according to a report published Tuesday.

Airlines intent on making on-time departures are saying no to more fliers who don't check-in on time, according to a USA Today report.

"They're absolutely getting stricter," Terry Trippler, an air travel expert at Cheapseats.com told the newspaper.

Missing a flight can translate into added costs in the form of ticket-change fees and fare differences, the report said. But airlines consider each passenger's reason for late arrival and can also choose to waive the added costs, it said.

The newspaper conducted a survey of the check-in policies of 18 U.S. airlines and found that fewer than half of the airlines guarantee that a passenger who misses a flight will be booked on the next available flight for no charge.

Airlines say their late check-in policies are flexible, the newspaper reported. A Continental Airlines spokeswoman told the newspaper that late passengers may be denied boarding and charged a fee but are generally accommodated on the next flight without charge.

A United spokeswoman said in the report that United won't book late-arriving passengers for free on another airline's flight.

Travelers who like to cut it close at the airport should check-in online and print out their boarding pass before arriving at the airport, Charles Franklin, a travel manager for an auto manufacturer, recommended in the report.

Printing out a boarding pass ahead of time allows fliers to go directly to the gate without having to meet an airline's ticket counter check-in time, USA Today said.

Fliers should also keep track of check-in requirements, which can vary. For example, passengers flying Delta Air Lines with no bags to check have to show up at the ticket counter 15 minutes before most domestic flights, while those with bags to check are required to arrive 30 minutes in advance, the report said.

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