There are a lot of debates about the right and wrong behavior when flying. Is it OK to recline your seat, for example, or should the window shade be up or down?

These are all hot topics that stir a lot of controversy, along with other bigger questions like whether parents should get to sit with their kids without paying an extra fee or if it’s ever OK to ask someone to change seats.

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However, there’s one even bigger debate that has especially high stakes. That’s the question of just how early you need to be checked in at the airport.

Of course, the official recommendation is to arrive and check in at least two hours before your scheduled flight. That way, you have plenty of time to get through security, maybe grab a bite to eat, and get to the gate to board on schedule without worrying about missing your flight.

Related: Southwest Airlines adds strict new onboard rule

However, while a survey conducted by Go Airport Express found that over 71% of travelers follow that recommendation and come at least two hours ahead of schedule, that means over a quarter of flyers cut things closer.

Now, a new United Airlines rule may affect those later arrivers – and it’s a rule every traveler needs to be aware of so they are not accidentally left stranded.

You’d better be prepared to check in a little earlier for your United Airlines flight.

Image source: United Airlines

New United Airlines rule changes your check-in time

United Airlines is putting a new policy in place regarding the time by when you must be checked in if you actually want to be allowed to board your flight.

Under the current policy, you must be checked in for a domestic flight at least 45 minutes prior to departure if you have a checked bag. If you do not have a bag to check, you only need to be checked in 30 minutes ahead of departure (although certain airports have their own policies with an earlier deadline).

Related: American Airlines quietly tests surprising change to meals on some flights

Starting June 3, 2025, however, the 30-minute rule for those without a bag no longer applies. In a memo to gate agents, United Airlines explained that all customers now must be checked in 45 minutes before departure – a full 15 minutes earlier than under the prior rules.

United Airlines explained that this policy shift is intended to simplify and streamline operations.

“We are consolidating the four existing domestic cut-off times into a single, consistent time — 45 minutes before departure for all domestic passengers. This adjustment also provides our airport Customer Service representatives additional time to assist customers prior to departure,” the United Airlines memo to gate agents read.

The new United Airlines rule has been a long time coming

United Airlines has been setting the stage for this rule for a long time. 

In fact, United updated its contract of carriage with passengers as far back as last summer. When the update rolled out, the new contract said the airline could actually require passengers to be checked in as much as 60 minutes before the time the plane actually departs.

Related: American Airlines reverses unpopular policy, angers workers

However, while the contact terms were altered a long while ago, the company said it was not making an immediate change – and because some passengers had already booked travel more than a year out under the old rules, the airline had to wait until June of 2025 to modify the boarding policy.

More on travel:

• U.S. government issues serious warning for cruise passengers
• Delta Air Lines makes a baggage change that travelers will like
• United Airlines passenger incident triggers quick response

Beginning June 3, however, the date has officially arrived. So if you are someone who like to cut things close, make sure you know the new policy, because that 15-minute period could make the difference between being allowed to board your flight and being left stranded.