Millions of UK holidaymakers could be owed a combined £44.7 million in Air Passenger Duty refunds, new research has found.

The study found that one in 10 Brits could be eligible, but that more than three-quarters of us were unaware we may be owed a refund from our airlines.

Air Passenger Duty (APD), sometimes referred to as airport tax, is an excise tax on flights from the UK designed to raise funds for the government and encourage the use of more sustainable modes of transport.

Although airlines are required to pay the tax, the expense is often passed on to the customer in the ticket price.

However, the tax is only payable once the traveller has flown, meaning anyone who bought a ticket but then didn’t travel should be able to claim back the tax – even on a non-refundable ticket.

Go.Compare found that as many as 3.6 million UK adults could be owed the refund without even realising.

It is now urging everyone to check if they could be entitled to claim their money back.

Holidaymakers could be reimbursed for the tax if they missed a flight and had to buy a second ticket, cancelled a booking for a non-refundable plane ticket or didn’t fly because their flight was cancelled.

Eligible travellers could be owed up to £224 depending on the destination and flight class of their journey, and can claim by contacting the airline and providing their trip details.

More information on how to claim an APD refund can be found on Go.Compare’s website.

Rhys Jones, travel insurance expert at Go.Compare, says: “Very few travellers know what Air Passenger Duty is and understand how it works. This means millions could be entitled to some money from their airline without even realising it.

“Your eligibility for the refund and how much you can claim depends on the circumstances of your trip, so you will need to check if you’re entitled to anything first.

“Keep in mind that you’ll likely only be refunded if you didn’t travel, so if you were placed on another flight as a result of a cancellation, for instance, you probably won’t be eligible, since you still flew.

“But, if for example you missed your flight and had to buy another ticket for a later departure, you could claim back the tax on the original ticket, as you paid the APD twice but only flew once.

“Some airlines do impose a deadline and an admin fee to claim, which can mean it isn’t worthwhile for some trips, but not all of them do this, so it’s worth looking into for your journey.

“You won’t be able to claim for any knock-on expenses as a result of an incomplete journey here either, that’s what your travel insurance is for. But, it’s a great way to take the sting out of a disappointing day at the airport.”