Southwest pledged to provide refunds to passengers on canceled or significantly delayed flights between Dec. 24 and Jan. 2, but the airline is also providing reimbursement for additional expenses including the cost of staying at a hotel or renting a car. Passengers were also given 25,000 frequent-flier points in a move by Southwest executives to win them back.

Airline passengers “have very few rights,” said

Paul Hudson,

president of FlyersRights, a consumer advocacy organization. Getting the remuneration that passengers believe they are entitled to can come down to perseverance and communicating extensively with the airline over an extended period.

Here’s what travelers need to know about their rights on domestic flights in the U.S. and how to get reimbursed.

My flight was canceled. Can I get a refund?

Airline customers are entitled to a refund if a flight is canceled for any reason or “significantly delayed” and they opt not to travel, according to rules from the Transportation Department. This policy extends to nonrefundable tickets. The DOT determines on a case-by-case basis whether passengers are entitled to a refund for a delayed flight.

While airlines are required to provide refunds in these circumstances if requested, they aren’t barred from offering other forms of redress first. Carriers will often offer a passenger the opportunity to rebook on another flight or a voucher or credit that could be used for future travel.

In these situations, customers will need to speak with an airline representative and request an “involuntary refund,” Mr. Hudson said. Not all customer-service staff will be familiar with this phrase, he warned, but he described it as “the magic words” to use to get a refund quickly.

I had to stay in a hotel because of a flight delay. Am I entitled to reimbursement?

Additional compensation beyond a refund of airfare and other fees isn’t required by the DOT. Still, most airlines have policies on what they will cover.

If a plane has a technical issue or the flight isn’t properly staffed, an airline’s compensation policy typically will kick in. If the delay or cancellation is due to weather, passengers may be out of luck getting assistance.

The DOT maintains a dashboard spelling out what is covered under the customer-service policies at the 10 largest domestic airlines in the U.S. in cases where cancellations or delays were under the carrier’s control. Each of these major airlines has put these policies in writing, making the commitments enforceable, a DOT spokeswoman said in an email.

My checked luggage went missing. What does the airline owe me?

If a checked bag is delayed, missing or damaged, the airline is liable and must reimburse the traveler. For domestic flights, airlines are only required to cover up to $3,800.

Apart from being required to reimburse passengers for the value of items that were lost or damaged, carriers must also compensate people for incidental expenses such as purchasing replacement clothing or medications. Airlines cannot set an arbitrary daily limit for those expenses, though they can require receipts or other proof for valuable items that were lost, according to the DOT.

I can’t rebook with my airline. Are they required to book me on another airline?

Before the airline industry was deregulated in the U.S. in the 1970s, carriers were required to rebook passengers with other airlines in instances where flights were canceled or delayed. “Now, it’s strictly voluntary,” said Mr. Hudson.

Some carriers have formal relationships with other airlines that allow them to rebook reservations at no additional cost, whereas others may buy tickets from competitors for stranded passengers. Southwest said it bought tickets on other airlines during its meltdown, and

Spirit

did the same during its 2021 meltdown.

I was bumped from my flight by my airline. Is that allowed?

Airlines have come under fire in recent years for the practice of overselling flights and then bumping passengers. The practice is allowed, as long as you haven’t boarded the plane. If you’ve already boarded, the airline can remove you from the flight for safety, security or health reasons.

If a passenger is involuntarily bumped, the carrier must provide a written statement of the flier’s rights and how the company decides who is bumped. They may be provided a refund, but they aren’t guaranteed additional compensation.

To be eligible for compensation, the traveler must have a confirmed reservation, have checked in on time and have arrived at the departure gate on time, the DOT states on its website.  

If all those conditions apply—and the airline cannot rebook the passenger on a flight that gets them to their destination within one hour of their original scheduled arrival—compensation is calculated based on the price of the original ticket, the length of the delay and whether the flight is domestic or international. Compensation ranges from up to $775 for short delays to no more than $1,550 for longer delays.

Write to Jacob Passy at jacob.passy@wsj.com