Don’t expect that practice to last forever. Travelers still have a chance at scoring record-low fares, and frequent-flier miles and status should be safe through at least 2021. But surcharges for changing or canceling a ticket will eventually come back.

“Certainly, COVID-19 has ushered in new terrain when it comes to flex policies, with the big difference being that we don’t really have a set end date for something like this,” says Melissa Dohmen, senior manager of communications at travel fare aggregator Orbitz. “I think one could speculate that some version of flex policies will remain in effect at least through the end of the year for travel in the U.S. Internationally, we may see airlines curtail some of these policies sooner based on local conditions and their ability to mitigate the spread of the virus.”

Several of the top major domestic carriers are scheduled to see the deadline for waivers on fee changes on new tickets run up on July 31, even as new cases of COVID-19 continue to skyrocket across the United States, and it’s up in the air if carriers will extend this grace period.

Navigating these policies by carrier, by cabin, and even by original booking date is a time-intensive and byzantine process. Alaska Airlines, for example, is continuing to waive fees on changes to new tickets booked by July 31, 2020, for travel through June 30, 2021. But lower-priced “Saver” fares do not qualify for itinerary changes. Passengers can cancel the trip but receive only a credit for the value of the ticket.

American Airlines is offering a similar policy for future travel booked by the end of July, although passengers can make changes without penalty and push back travel to as late as Dec. 31, 2021. Customers are allowed to change their origin and destination cities as part of this offer.

United Airlines is a bit trickier: Any tickets purchased by July 31 can be canceled or changed without any fees. But if a passenger rebooks a flight, they will have to pay the fare difference between the original ticket and the new one, and they will not be issued a credit or refund if the new itinerary costs less than the original booking.

At Delta Air Lines, any tickets purchased by July 31 for future travel can be canceled or changed for up to a year from the date of purchase without any fees. But a Delta spokesperson told Fortune that the carrier is evaluating an extension of its change fee waiver. 

JetBlue Airlines also originally had an end date set for July 31 but has since extended its no-fee offer for future changes to new and existing bookings, although fare differences may apply. Fliers now have through at least Sept. 8 for rebooking flights scheduled through the end of JetBlue’s current schedule, which for the time being runs through February 2021.

Orbitz recently launched a new search filter in response to COVID-19 that allows travelers to narrow flight search results to show only tickets with flexible change policies or no change fees. Moving forward, Dohmen says, travelers might be less inclined to purchase economy fares that are restrictive, opting instead to pay a little more for extra flexibility to change plans without penalty.

“I don’t know that anyone would have predicted in March—when the travel industry first started implementing flex policies in response to COVID-19—that they would still be in place throughout the summer,” Dohmen says. “So in many regards, I think the flexibility we’ve seen so far is a positive signal for travelers booking travel into the fall and beyond. That said, in the U.S., where we have seen conditions change from destination to destination and week to week, I do think this event will change how many travelers shop for flights.”

Regardless, airlines are desperate to get passengers in seats (even middle seats, despite social distancing guidance) to slow the bleeding of their bottom lines. Saniya Shah, CEO of Pilota, a venture-backed travel tech startup based in New York City, says airlines will keep these policies in place for the foreseeable future to encourage customers who are considering taking a flight to complete their bookings. However, Shah warns, airlines will likely continue to incrementally extend the timelines for altering a reservation rather than announce these decisions well in advance.

“Airlines are going to be lenient with these policies until an end to the pandemic is in sight,” Shah says. “Until then, people are going to be wary about flying, and unless they know that their ticket value is safe, they will be very hesitant to complete any bookings.”

There is still an incentive for travelers to book travel now with the assurance it won’t cost much, if anything, to change plans, advises Mike Taylor, senior and practice lead for travel intelligence at J.D. Power. “As volume and demand increase, it would be our assumption that the ‘cost’ of this incentive to the airlines will start to outweigh the value of the incentive in bookings.”

Taylor explains that change fees are major revenue generators for many airlines and, as such, would be hard to give up. J.D. Power research indicates that the costs and fees associated with an airline journey have the biggest impact on travelers’ satisfaction with an airline. Southwest, for example, ranks highly with consumers when factoring the value and cost of a ticket—not because the carrier’s fares are significantly cheaper than most other airlines, but because Southwest generally waives change fees and uses the absence of baggage fees as a marketing hook.

“If other airlines want to continue with fee waivers, it should have a positive effect on their passengers’ satisfaction,” Taylor says. “But this comes at a year-over-year revenue cost that would give most CFOs pause.”

When penalties do return, the onus will be back on passengers to dispute any fees they feel are unwarranted. There has always been some wiggle room, especially for citizens of the European Union and also passengers traveling on European carriers to and from the EU, where travelers’ rights are more protected by law.

There is also the usual fallback of travel insurance, sometimes provided by major credit cards but also through insurance providers. Before the arrival of COVID-19, however, travel insurance covering trips thwarted by a pandemic was about as common as home or renters insurance covering damage incurred by an earthquake. (West Coast residents will know this to mean nonexistent.)

“Most travel insurance policies came out with clauses that did not cover COVID-related issues back in March, especially the ‘cancel for any reason’ policies,” Shah says. “That is why it is really important for travelers to carefully read through their policies to understand what the limitations are for post-COVID travel, specifically as to whether canceled or affected trips will be covered, as well as whether their travel health plans will cover any COVID-related complications.”