United Airlines passengers are facing a big change beginning Tuesday as the airline shifts how early fliers must check-in for trips.

If passengers don't abide by the new rules, United says, their flight could be canceled.

Stream Los Angeles News for free, 24/7, wherever you are. WATCH HERE

Effective Tuesday, June 3, United’s “check-in cutoff" for most U.S. flights will be 45 minutes before departure. Luggage also must be checked at least 45 minutes before the flight takes off, United said.

Previously, the cut-off was 30 minutes.

Get top local stories in Southern California delivered to you every morning with NBC LA's News Headlines newsletter. SIGN UP

Customers can still use the United app to check in up to 24-hours before their flight, the airline said.

While the new cutoff

See Full Page