Millions of London commuters can pocket their share of the quarter of a billion pounds that's sloshing around on unused Oyster cards, after Transport for London's (TfL's) latest figures showed the pot of unclaimed cash increased by more than £50 million over the last 12 months.

TfL is now sitting on more than £223 million in unused Oyster card credit belonging to people who have loaded a card but are no longer using it – yet fortunately reclaiming your forgotten credit couldn't be simpler.

Oyster cards can be used across all TfL services and there are more than 63 million cards currently in use. On top of that, there are more than 41 million 'dormant' cards (which haven't been used in the last 12 months).

To activate an Oyster card a user must first pay a £5 deposit (it's a £3 deposit for a 'visitor' Oyster card used by tourists) before topping it up to pay for fares in and around the capital.

According to TfL's own figures, as of 30 June 2016, the total pay-as-you-go balance on dormant cards totalled more than £111 million, while total deposits lying untouched was north of £112 million. The figures also show that the average balance per dormant card (not including the £5 deposit) is £2.66.

For detailed info on Oyster card refunds for old cards, overcharges and delays, check out our 60-second guide.

How do I find out how much I've got on an old Oyster card?

You can find out how much money you've got on an Oyster card at ticket machines by holding your card against the yellow Oyster card reader. Or you can check your balance anytime online if you register your Oyster card and have an account. If you haven't already you can do that on the TfL website.

How do I get a refund?

There are a number of ways you can reclaim dormant Oyster deposits and credit:

Online. You'll need to have an account and register your Oyster card. Once you're signed in to your account you just need to select your Oyster card, click on 'apply for a product refund' and follow the instructions.

Once you do this your Oyster card will stop working and you'll be refunded any pay-as-you-go credit, or unused travelcards, and your deposit. You can then request how you want your refund paid.

By phone. You can call TfL customer services on 0343 222 1234 (check call charges on its site); you'll need to confirm you're the registered owner of the Oyster card and provide the following details:

  • Your Oyster card number
  • The answer to the security question you'd selected

If you don't have this information, customer services will ask you some other questions to find your card and identify you as the registered owner.

At the ticket machine. If you no longer need your Oyster card, you can get your pay-as-you-go credit (up to £10) and your deposit refunded at a ticket machine. But if you've also got a season ticket of any sort you won't be able to get a refund at the ticket machine and you'll have to try one of the other channels.

Just touch your Oyster card on the yellow card reader on the ticket machine, select 'Oyster refund' and follow the on-screen instructions.

If you only have pay-as-you-go credit on your Oyster card and get a refund, you won't be able to use your Oyster card again. Make sure you no longer need it before you get a refund. Refunds are paid in cash dispensed from the ticket machine.

By post. You'll need to write a letter stating that you want a refund and send your Oyster card to:

TfL Customer Services
4th Floor
14 Pier Walk
SE10 0ES

Is there a cut-off date for getting a refund?

There's no time limit so you can ask for a refund whenever you want, provided you're in credit.

Have you got an unused Oyster card lying around? You can claim part of £223m if so
A third of pay-as-you-go journeys in London are now made using a contactless bank card

What's behind the rapidly rising value of unused Oyster card credit?

A third of pay-as-you-go journeys are now made using a contactless bank card. As more people choose to use their contactless cards to avoid needing to top up an Oyster card, the amount of unused credit could continue to grow.

Another potential reason for this increase in credit is visitor Oyster cards. Huge numbers of tourists are reported to keep their Oyster cards as a memento after a trip to London and never bother getting a refund for unused credit. Meanwhile, some Londoners keep spare cards to lend to friends and visitors.

What does TfL say?

Shashi Verma, TfL's director of customer experience, says: "The credit balance on Oyster cards never runs out and customers can obtain a full refund whenever they wish. This is why we regularly publish the amount of credit left on Oyster cards, remind our customers that the credit never expires and provide information on how to get a full refund from Tube station ticket machines or by contacting our customer services team. 

"Customers who would prefer never to top up credit might consider using their contactless bank card instead, which charges the same as an Oyster fare but never needs topping up."