A major airline is changing its check-in policy to require earlier passenger arrivals.

Starting June 3, United Airlines will require customers without checked bags to check in for domestic flights at least 45 minutes before departure. United currently requires travelers to check in at least a half-hour before a flight, the Houston Chronicle reported.

“United has set time limits for when you can check in and check your bags. Some airports or flights have special time limits which depend on location. If you don’t meet your check-in time limits, we’ll do our best to find another option. However, we have the right to deny service which may result in cancellation of your reservation, denied boarding or the option to check your bags,” the airline’s website noted.

The check-in time for passengers for checked bags is also 45 minutes, according to United’s website. International flights require passengers to check in an hour before departure, with some areas, such as flights to or from Micronesia, Honolulu, or St. Thomas, having other regulations.

You can see the list of airport-specific check-in times here.

Check-in can start 24 hours ahead

United allows customers to start the check-in procedure online 24 hours before a flight.

Passengers are still advised to arrive at U.S. airports two hours early for domestic travel and 3 hours early for international travel to clear Transportation Security Administration clearances.

United recommends passengers arrive at the gate 15 minutes before boarding states for domestic flights and 30 minutes for international flights. Passengers are required to be on board 15 minutes before departure. United said.