TfL card clash

What card clash is

Contactless readers do not look inside your wallet and pick sensibly. They respond to whatever they can see, and if two cards are in range the result is unpredictable. Tap in with the wallet and one card answers. Tap out with the same wallet and a different one answers.

Now neither card has a complete journey. The first has a tap in with no tap out. The second has a tap out with no tap in. Both are treated as incomplete journeys, and both attract a maximum fare. For one trip you have paid two of the highest fares the system can charge.

It is not a fault in your cards and it is not something you did wrong. It is a limitation of how the readers work, and it is common enough that Transport for London gave it a name.

Although it has since taken the page down. The dedicated card clash page redirects to the general refunds hub now, and the term survives only as a subheading on a page about paying the right fare. The problem did not go away with the page.

Transport for London draws a distinction worth knowing. Card clash proper is two cards in a wallet, one of them read by mistake. Separate from it, and just as costly, is touching in with one device and out with another: an iPhone in and an Apple Watch out, or a phone in and a bank card out. Different cause, identical outcome, and the same refund route fixes both.

How to tell it happened

The signature is two charges for one trip, usually on the same day and often within a minute or two of each other, sitting on different cards. If you only ever look at one card's statement you will see half of it and conclude you were charged a strange amount once.

In the journey history you will typically see a journey with an Unknown end on one card and a matching Unknown at the other end on the second card. Reading them side by side is what makes it obvious.

Getting the money back

Sign in at contactless.tfl.gov.uk and check the history for each card involved. You are looking to establish two things: which journey it was, and which two cards took part in it. With those, raise it with Transport for London and explain that the two charges are one journey split across two cards.

If both cards are already registered in the same online account this is straightforward. If one of them is not, you may have to add it, or contact customer services so they can see both sides. Our page on contacting Transport for London covers the route for that.

Two timings matter and they are the same as for any maximum fare. Wait 48 hours before claiming, because a good number of these correct themselves. And claim within eight weeks of the journey, which is the window Transport for London gives for the whole incomplete journey route.

Phones and watches make it worse

Paying by phone feels like it should remove the problem, and it often introduces one instead. A phone in the same hand as a wallet is two payment methods at the reader. A watch on the wrist of the hand holding a wallet is two as well.

The most reliable way to cause a clash is to hold your whole wallet against the reader with a phone in the same hand, which is exactly what most people do when they are in a hurry.

Stopping it happening again

The fix is unromantic. Pick one payment method for travel and present only that, out of the wallet, on its own. If you use a phone, put the wallet in the other hand. If you use a card, do not wave the whole wallet.

Consistency matters for a second reason, and it is the expensive one. Daily and weekly capping only works when every tap is on the same card, so spreading a week of travel across two cards can cost you the cap as well as the odd maximum fare. Worse, maximum fares do not count towards capping at all, so a clash both overcharges you and fails to move you closer to the ceiling that would have protected you.