There isn't one deadline for every flight cancellation. The answer depends on the airline, the route, and what you're claiming.

For a cancellation covered by U.S. Department of Transportation rules, a ticket refund is generally due automatically if you reject the replacement flight or travel credit. The airline must issue it within 7 business days for a credit-card purchase or 20 calendar days for most other payment methods.

EU261 and UK261 use a different system. Ticket reimbursement is generally due within seven days after you choose it. A separate fixed-compensation claim has no single EU-wide deadline; the limitation law of the relevant country controls. The Montreal Convention's two-year period applies to certain damages actions, not every canceled-flight refund or compensation claim.

Flight cancellation deadlines at a glance

U.S. flight cancellation refund rules

The main U.S. rule is the Department of Transportation's Refunds and Other Consumer Protections rule. TSA does not set airline refund deadlines; the DOT does.

When a U.S. refund is required

You can generally choose a refund when the airline:

• Cancels your flight.
• Makes a significant change and you no longer want to travel.
• Fails to provide a paid ancillary service, such as a checked-bag or seat service, when the rule requires a refund for that unused service.

DOT examples of a significant change include a domestic schedule change of at least three hours, an international change of at least six hours, a different airport, an added connection, or a downgrade in travel class. The result still depends on the details of the itinerary and the change.

The reason for the cancellation usually doesn't remove the ticket-refund right. Weather, air-traffic restrictions, staffing issues, and maintenance problems can affect whether the airline owes meals, a hotel, or other assistance, but an eligible refund can still be due when the airline cancels the transportation and you decline the alternative.

The refund generally goes back to the original form of payment. A voucher or travel credit can replace it only if you agree to accept that option. If you want a refund instead, don't accept a credit before you've made that choice.

How long does a U.S. airline have to issue the refund?

The DOT rule sets two main payment deadlines:

• Seven business days for a credit-card purchase.
• Twenty calendar days for other payment methods, including debit card, cash, check, and certain electronic payments.

Those are payment-processing deadlines, not a seven-day deadline for you to submit a request. The rule calls for an automatic refund in covered cases, but a prompt written request gives you a useful record. State that the airline canceled or significantly changed the flight, that you did not accept alternative transportation or a credit, and that you want the refund in the original form of payment.

If an online travel agency charged your card, send the request to the seller named on your receipt and copy the airline when practical. The business that processed the payment may control the refund workflow, so keep its confirmation and claim number.

The U.S. 24-hour cancellation rule is separate

The 24-hour rule covers a change of mind after booking. For an airline ticket purchased at least seven days before departure, the airline must either:

1. Allow cancellation within 24 hours for a full refund; or
2. Hold the reservation for 24 hours without requiring payment.

This is not a 24-hour deadline for requesting a refund after the airline cancels your flight. The rule also generally doesn't cover tickets bought through a travel agent or online travel agency. Check the terms of the seller that issued the booking.

If you voluntarily cancel a nonrefundable ticket outside that window, there is no broad federal right to a cash refund. The fare rules, the airline's voluntary policy, and any travel insurance may determine what you can recover.

U.S. compensation, meals, and complaints

The United States has no general federal system requiring airlines to pay fixed cash compensation for an ordinary flight cancellation. An airline may offer miles, credits, meals, hotels, or other help under its own customer-service policy. Those offers are separate from the DOT refund right.

If the airline denies an eligible refund, complain to the airline first. If it still refuses or delays payment, submit a complaint through the DOT's Air Travel Complaint process. A DOT complaint can document a possible violation, but it isn't the same as filing a court case and may not preserve a deadline for a private lawsuit.

EU261 and UK261 cancellation rights

EU261 and UK261 are regional passenger-rights systems. They don't apply to every international flight.

EU261 generally covers flights departing from the EU, Iceland, Norway, or Switzerland. It can also cover some flights arriving there from outside the region when operated by a qualifying carrier.

UK261 generally covers flights departing the United Kingdom and some flights arriving in the UK from abroad when operated by a qualifying UK carrier. The Your Europe air-passenger FAQ and the UK Civil Aviation Authority's cancellation guidance explain the main coverage and remedy rules.

Refund, rerouting, and care

When a covered airline cancels a flight, you normally choose among:

• Reimbursement of the ticket price, generally within seven days.
• Rerouting to the final destination at the earliest opportunity.
• Rerouting at a later date that suits you, subject to seat availability.

If you wait for rerouting, the airline may also owe meals, refreshments, communication, accommodation, and transport between the airport and hotel when necessary. When the airline doesn't provide that care, pay only reasonable and necessary costs, ask the airline for help first if you can, and keep itemized receipts.

An extraordinary circumstance can remove the fixed-compensation obligation, but it usually doesn't remove the right to reimbursement or basic care while you wait for rerouting.

Reimbursement and fixed compensation are separate. You may qualify for a ticket refund and compensation, or choose to take a replacement flight and still qualify for compensation.

When is EU261 or UK261 cancellation compensation due?

A cancellation announced at least 14 days before departure normally doesn't qualify for fixed compensation. With less notice, the replacement flight's timing matters:

If the replacement misses those limits, compensation may be payable unless the airline proves extraordinary circumstances. Keep the cancellation email, text message, or app notification and its timestamp. The airline may have to show when it informed you.

The standard compensation bands are:

These amounts are generally per passenger. Route category matters too. For example, under EU261, an intra-EU flight over 1,500 km falls into the EUR 400 band rather than automatically qualifying for EUR 600. A qualifying rerouted flight can also reduce compensation by 50 percent if it reaches the destination within the regulation's specified time limit.

Suppose an airline gives notice 10 days before departure and offers a replacement that arrives five hours after the original scheduled arrival. That may pass the notice and arrival test if the replacement doesn't leave more than two hours early. The airline could still avoid compensation by proving an extraordinary circumstance.

What counts as an extraordinary circumstance?

An extraordinary circumstance can remove the fixed-compensation obligation when it caused the cancellation and reasonable measures couldn't have prevented it. Examples that may qualify include:

• Severe weather that makes the flight unsafe.
• Air-traffic-control restrictions.
• Security risks or airspace closures.
• Some strikes by airport personnel or air-traffic controllers outside the airline's control.

Routine technical problems, poor maintenance, and strikes involving the airline's own employees generally don't qualify automatically. The airline can't rely on a label such as "operational reasons" without explaining the event and its connection to the cancellation.

EU and UK flight compensation claim limits

EU261 doesn't set one universal deadline for bringing a compensation claim. National limitation law controls. The result can depend on the country connected to the flight, the type of claim, how the period is calculated, and whether a formal procedure suspends time.

A table claiming that every EU261 claim lasts two, three, or five years can therefore be wrong. The Montreal Convention's two-year limit isn't automatically the EU261 deadline.

In England and Wales, six years is commonly applied to many EU261 and UK261 court claims. Scotland uses a different prescription system, so don't carry the six-year figure across the whole United Kingdom. A regulator or alternative-dispute-resolution scheme may also impose its own submission window, which can be shorter than the time for starting a court claim.

Don't assume that an email to the airline, a regulator complaint, or a claims company's involvement pauses the court limitation period. In some jurisdictions, a formal ADR or court procedure can affect the calculation. An ordinary customer-service message may not. If the date is close, check the rule for the relevant court and consider local legal help.

Why the Montreal Convention's two-year limit is different

The Montreal Convention governs certain international-carriage claims, including some claims involving delay, baggage loss or damage, and passenger injury. For an action covered by the Convention, Article 35 generally requires the case to be brought within two years, calculated under the Convention's timing rules.

It does not:

• Create a universal refund deadline after an airline cancellation.
• Set the fixed EU261 or UK261 compensation amounts.
• Replace every country's limitation period for a passenger-rights claim.
• Guarantee compensation simply because a flight was international.

One canceled itinerary can raise several different claims. Identify whether you're seeking a ticket refund, EU261 or UK261 compensation, reimbursement of care expenses, or damages for a proven financial loss before choosing a deadline.

How to claim a flight cancellation refund or compensation

1. Save the evidence

Keep copies of:

• The booking confirmation, ticket number, and payment record.
• The cancellation notice and the time you received it.
• The original schedule and every rerouting offer.
• Boarding passes and proof of your actual arrival time.
• Receipts for meals, lodging, ground transport, and other necessary costs.
• Emails, chat transcripts, claim numbers, and the airline's stated reason.
• Any voucher or credit offer you declined or accepted.

2. Separate the requests

A refund, fixed compensation, expense reimbursement, travel-insurance claim, and card dispute are different matters. Say which ones you're making.

For a U.S. refund, explain that the airline canceled or significantly changed the flight, that you didn't accept alternative transportation or a travel credit, and that you want the eligible amount returned to the original payment method.

For an EU261 or UK261 claim, ask separately for:

• Reimbursement or rerouting under the applicable passenger-rights regulation.
• Reimbursement of reasonable care expenses.
• Fixed compensation, if the notice and replacement-flight tests are met.

3. Submit the claim in writing

Use the airline's online claim form or email, then save the confirmation page and reference number. If a travel agency sold the ticket, submit the request there as well.

A concise request can say:

I am requesting reimbursement for the canceled flight listed below. I did not accept a travel credit. Please confirm the amount due, the payment method, and the date the refund was issued. I am also requesting any applicable passenger-rights compensation and reimbursement of the attached reasonable expenses.

Upload readable copies rather than original receipts, and retain the originals.

4. Escalate if the airline doesn't respond

• United States: Follow up after the applicable DOT payment period. If the airline still refuses or delays an eligible refund, submit a DOT complaint. Ask your card issuer about its dispute process promptly; card-dispute deadlines are separate from DOT deadlines.
• European Union: Contact the relevant national enforcement body, usually connected to the departure country. For a cross-border dispute, the European Consumer Centre may help identify the appropriate route.
• United Kingdom: Complain to the airline, then use its approved ADR provider if one is available. The CAA's cancellation and delay guidance explains the UK process and compensation bands.

A regulator may investigate compliance without recovering the money for you. ADR or a court may be needed for actual payment.

5. Calendar the earliest possible deadline

Record the flight date, the date and time you learned of the cancellation, the date you chose reimbursement, the date you submitted the claim, and any response deadline. If a court limitation date is approaching, don't wait for an airline escalation, regulator, or claims company to act. Check whether a formal filing is required to preserve the claim.

What happens if you miss the deadline?

A missed date doesn't always prevent you from asking an airline for a voluntary refund. In the United States, the DOT's seven-business-day period is generally a payment limit, not a passenger filing cutoff. The airline can still review a late request, although other fare terms, evidence problems, or legal limits may affect the result.

For EU261 and UK261 compensation, a court may reject or time-bar a claim filed after the applicable national limitation period. The same risk applies to a Montreal Convention damages action filed after two years. A claims service can't create a longer legal period, and accepting a voucher or settlement may affect later rights.

If your deadline is close, submit the airline claim now, preserve every document, and verify the correct court or ADR procedure for the jurisdiction involved. This is general consumer information, not legal advice.