With the busy travel rush underway, this holiday season marks the first with new federal refund regulations in effect for U.S. airlines.

Passengers who opt to not rebook are now entitled to an automatic refund if their flight is significantly delayed or canceled. The Department of Transportation rule requiring airlines to issue refunds -- not vouchers -- went into effect in October.

"We saw this a lot during the COVID pandemic, airlines would try to issue trip credits instead of giving you cash refunds," said Clint Henderson with The Points Guy travel website. "And the government wants that kind of behavior to stop."

The new rule mandates airlines issue refunds without passengers needing to ask. Refunds must be issued within seven business days if the passenger paid by credit card and within 20 calendar days for other forms of payment.

"Significant" disruption is now clearly defined under these new rules, Henderson said, being three hours or more for domestic flights and six hours or more for international flights. Prior, those time windows varied by airline.

Henderson said it's also important to remember these easier refund rules extend beyond the ticket itself.

"If you paid for a seat assignment, you paid for Wi-Fi, if you got any of the goodies ahead of time that you did not end up receiving, then you are entitled to a refund for those charges as well, and that includes baggage fees," he said.

The TSA said it expected to screen nearly 40 million travelers at airport security checkpoints during the holidays through Jan. 2. Despite that record number, 2024 remains on track to have the lowest rate of flight cancellations in nearly a decade, according to the Department of Transportation.