If you're asking how long you have to complain about a delayed flight, there isn't one worldwide deadline. First separate an airline complaint from a legal limitation period: the complaint may be part of the carrier's internal process, while the limitation period controls when a court claim must be brought.

The answer also depends on what you're seeking:

If you're pursuing a claim now, submit it in writing promptly. An airline form, a regulator complaint, and a court action are separate steps. Don't assume that an email or customer-service form pauses or extends a legal deadline.

Quick answer: delayed-flight claim deadlines

Claim route General position What matters
EU261 compensation No single EU-wide deadline The limitation law of the relevant country controls. Regulation 261/2004 does not set one universal filing period.
UK261 compensation Commonly up to six years in England and Wales The applicable UK jurisdiction matters. Do not automatically apply six years in Scotland or elsewhere.
U.S. airline or DOT complaint No single federal deadline for every delay issue Refund requests, contract claims, and DOT complaints follow different rules. File as soon as possible.
Montreal Convention damages Two years to bring a court action Article 35 generally measures the period from arrival, expected arrival, or the date carriage stopped.
Airline claim form May have an internal submission target A carrier's customer-service deadline is not necessarily the legal limitation period.

The EU Regulation 261/2004 text, UK Civil Aviation Authority guidance, and Montreal Convention text are better starting points than a generic deadline calculator.

Identify the type of claim first

A delayed flight can create several different requests:

These remedies aren't interchangeable. The Montreal Convention doesn't automatically provide the fixed EUR 250 to EUR 600 payments available under EU261. Similarly, a DOT complaint isn't the same as filing a lawsuit for a contract or damages claim.

EU261 and UK261: when a three-hour delay qualifies

Under EU261, a passenger may generally claim fixed compensation when they arrive at their final destination at least three hours late and the airline can't establish extraordinary circumstances. For a connecting itinerary booked as one reservation, measure the delay at the final destination. Separate tickets are usually assessed separately.

EU261 generally applies to:

The EEA and Swiss passenger-rights arrangements can affect coverage depending on the route. UK flights are assessed under UK261 rules where those rules apply.

UK261 generally applies to:

The operating carrier and route matter more than where you bought the ticket or which company issued it.

EU261 compensation amounts

Qualifying distance Standard compensation
1,500 km or less EUR 250 per passenger
More than 1,500 km within the EU, or 1,500 to 3,500 km on other covered flights EUR 400 per passenger
More than 3,500 km outside the EU EUR 600 per passenger

The amount isn't tied to the ticket price. If the airline reroutes you and you reach your destination within specified time limits, it may reduce the payment by 50%. Ask the airline to show how it calculated the distance and any reduction.

UK261 compensation amounts

The CAA lists these amounts for qualifying UK261 delays:

Flight distance Arrival delay Compensation
Under 1,500 km At least 3 hours GBP 220
1,500 to 3,500 km At least 3 hours GBP 350
Over 3,500 km More than 3 but no more than 4 hours GBP 260
Over 3,500 km More than 4 hours GBP 520

UK consumer guidance, including Which? information on delayed flights, commonly refers to up to six years for a claim in England and Wales. That isn't a universal rule for every UK court or circumstance. Check the jurisdiction before relying on a six-year period, particularly if the claim relates to Scotland.

What counts as an extraordinary circumstance?

Examples can include severe weather, air-traffic-control restrictions, security events, and some strikes outside the airline's control. Ask the carrier to identify the specific event and explain how it caused your delay.

A routine maintenance problem isn't automatically extraordinary. The Your Europe air-passenger-rights FAQ notes that a failure to maintain an aircraft correctly generally can't be treated as an extraordinary circumstance. A label in a rejection email isn't a substitute for an explanation.

Care and refunds are separate from fixed compensation

Even when a delay doesn't qualify for fixed compensation, EU and UK rules can still require assistance. Depending on the route, the waiting-time threshold is usually:

Assistance can include:

If the airline provides no assistance, buy only reasonable essentials and keep itemised receipts. Reimbursement isn't a blank cheque for premium meals, alcohol, or luxury accommodation.

When a delay reaches at least five hours, EU and UK passengers may be able to choose reimbursement for an unused part of the ticket instead of continuing the journey. A refund is different from fixed compensation. In some cases, a passenger can receive both a qualifying refund or expense reimbursement and statutory compensation.

U.S. flight-delay complaints: refunds aren't compensation

The United States doesn't have a general federal system that pays fixed cash compensation for an ordinary flight delay. An airline may offer meals, hotels, travel credits, or other help under its own policy, but those offers aren't the same as an EU261-style statutory payment.

U.S. Department of Transportation refund rules generally apply when an airline cancels a flight or makes a significant change and the passenger chooses not to accept the replacement transportation. Examples of a significant change can include an arrival at least three hours later on a domestic itinerary, six hours later on an international itinerary, or certain airport and connection changes.

That remedy is a ticket refund, not compensation for inconvenience. If you accept the replacement flight and travel, don't assume that a full refund remains available. Ask the airline to state which refund rule or policy it is applying and where the money will be sent.

There is no single federal deadline for every U.S. delay complaint, refund request, or lawsuit. File with the airline while the booking records are available. If the airline doesn't resolve a possible DOT violation, you can submit a complaint to the U.S. Department of Transportation. A DOT complaint may support regulatory review, but it doesn't replace a deadline for pursuing a private claim.

Montreal Convention: the strict two-year court deadline

The Montreal Convention applies to qualifying international carriage and can make an airline liable for loss caused by delay. This is a damages remedy, so you generally need evidence of a real financial loss connected to the delay, such as reasonable additional transport or accommodation costs.

Article 35 gives a two-year period for bringing an action. The period is generally counted from the date of arrival at the destination, the date the aircraft should have arrived, or the date the carriage stopped. The treaty also includes liability limits and defenses, so don't assume that every expense will be recoverable.

The two-year rule concerns bringing a legal action. An airline complaint submitted shortly before the deadline may not be enough. If your claim is approaching two years, check the applicable court procedure immediately.

How to file a delayed-flight claim

1. Map the itinerary

Record:

This information helps determine whether EU261, UK261, U.S. refund rules, the Montreal Convention, or only the airline's contract applies.

2. Calculate the actual arrival delay

For EU and UK compensation, compare the scheduled arrival with the time you reached the final destination. Keep the airline's messages, airport screenshots, boarding passes, and any official delay record.

A late departure alone doesn't establish EU or UK compensation. A flight that leaves late but makes up time may not meet the three-hour arrival threshold.

3. Preserve evidence

Create one folder containing:

Write down what airline staff told you while the events are fresh. If the airline cites weather, staffing, maintenance, or air-traffic restrictions, save that explanation.

4. Submit a written claim

Use the operating airline's official claim form or customer-service channel. State the legal basis, the amount requested, and the documents attached. Ask the airline to explain any extraordinary-circumstances decision rather than accepting a generic rejection.

Keep a copy of the completed form and confirmation page. If you booked through a travel agency, contact the agency as well for ticketing or refund issues, but send a passenger-rights claim to the relevant airline.

5. Separate the money requests

List each request clearly:

Don't claim the same receipt under two headings. If you accepted a voucher, check whether it was offered as temporary assistance or as a full settlement.

6. Escalate before the deadline

If the airline rejects the claim, ask for the precise reason and supporting facts. Depending on the jurisdiction, possible next steps include:

A claims company or consumer service doesn't automatically extend a statutory deadline. Check its contract and make sure you know who is responsible for filing formal proceedings.

A practical complaint letter

Subject: Flight delay claim - [flight number], [date], [booking reference]

I travelled on flight [number] from [origin] to [destination] on [date].
The scheduled arrival time was [time]. I arrived at my final destination
at [time], a delay of [hours and minutes].

I request:
- [EU261 or UK261 compensation of EUR ___ or GBP ___, if applicable];
- reimbursement of the attached reasonable expenses totaling [amount]; and
- [a refund, if I declined qualifying replacement transportation].

If you rely on extraordinary circumstances, please identify the specific
event, explain how it caused this delay, and provide the relevant basis for
your decision.

The attached documents include my booking confirmation, boarding pass,
delay evidence, and receipts. Please respond in writing and provide a
claim reference.

Name:
Address:
Email:
Phone:

For a U.S. cancellation or significant schedule change, replace the EU or UK compensation request with a clear statement that you didn't accept the alternative transportation and are requesting a refund to the original form of payment.

Airline claim forms and voucher offers

Ryanair, easyJet, and other airlines may use different online portals, response procedures, and voucher offers. Those administrative processes don't create separate EU261 or UK261 compensation scales for a covered flight.

Use the airline's official form, save the submission confirmation, and read carefully before accepting a voucher marked as a full settlement. An airline policy can't replace mandatory EU or UK passenger rights with a lower payment.

Baggage delay is a separate claim

A delayed bag should be reported at the airport through a Property Irregularity Report, followed by a separate written claim with receipts for reasonable necessities. Baggage claims can have different notice periods from flight-delay compensation claims, so don't assume that filing one preserves the other.

Frequently asked questions

Does an airline complaint reset the legal deadline?

Not automatically. An online form or email may document your request, but you shouldn't assume it pauses the limitation clock. Check the law governing the claim, especially if the deadline is close.

Can I claim if the delay was caused by weather?

Under EU261 or UK261, severe weather may remove the right to fixed compensation. It doesn't necessarily remove the right to care, a qualifying refund, or reimbursement of reasonable expenses. Ask the airline to identify the exact event.

Can a U.S. passenger claim EUR 600 for a delay?

Only if the itinerary is covered by EU261 or another applicable passenger-rights regime. Buying a ticket in the United States doesn't, by itself, create an EU261 claim.

Is the Montreal Convention the same as EU261?

No. Montreal generally concerns documented loss on international carriage and has a two-year court deadline. EU261 provides fixed compensation and assistance on qualifying routes, subject to its own coverage and national limitation rules.

If a deadline is near, submit the airline claim today, save proof of submission, and verify the relevant court or regulator route. A customer-service form may not preserve a court claim.