Passengers with a canceled flight are entitled to a new flight on the same day of travel if one is available.
This is the case even if the only available flight is on a rival airline.
Passengers whose flight was canceled with little notice could be entitled to cash compensation.
Compensation varies depending on the distance of the canceled flight and should be at least £220.
This week, the Government ordered airlines to cancel flights in July and August now to avoid last-minute chaos.
The letter is thought to have been primarily addressed to easyJet due to the airline’s last minute cancellations.
However, TUI, Wizz Air and British Airways have also canceled flights as they struggle to cope with staff shortages.
An easyJet boss said security clearance was taken too long and trained staff were still unable to start work.
Rory Boland, editor of Which Travel? said on the cancellations: “Some holidaymakers have been notified on the day they were due to travel, which is totally unacceptable.
“We continue to hear concerning examples of the airline failing to fulfill its legal obligations to passengers and ignoring their rights.
“If a flight is canceled within 14 days of departure, passengers could be entitled to compensation and should be offered the option of being rerouted using another carrier if necessary.
“We know this requirement is not always being met, so the government and Civil Aviation Authority must intervene where airlines are playing fast and loose with the rules.”