Oyster card users may be paying up to £91.80 a week more than passengers who pay for journeys using contactless cards at barriers.
The discrepancy is caused by differences in how payments are capped. Oyster card spending is capped daily, whereas contactless card payments are capped weekly.
This means that passengers travelling between zones 4 and 7 during peak times seven days a week would pay £121.20 if they paid using Oyster, as all the individual journeys add up. But if they were to use contactless, the same journeys would cost just £29.40 by the end of the week due to the weekly spending cap.
The research which has been done by the Labour party also showed that commuting from zones 1-4 over seven days would cost Oyster users £74.20, while contactless card users would pay just £45.
According to the BBC, London Assembly Member Val Shawcross said: “Boris Johnson has repeatedly said that Oyster would always be the cheapest way to travel but that simply isn’t true.
“When Boris Johnson launched contactless he could have chosen to add weekly caps to the Oyster card.
“Instead he purposely chose to give contactless card users a better deal, despite almost half a million Londoners not having a bank account let alone a contactless card.”
TfL director of customer experience Shashi Verma said: “The same fares apply to both contactless and Oyster.”
However, in order to pay the same amounts, Oyster customers must actively choose to buy a weekly Travelcard on their Oyster card. For contactless customers, the weekly cap makes this an automatic process.
“If a customer buys a weekly Travelcard on their Oyster card for zones 4 to 7 they will also pay the same fare of £29.40,” Verma added.
“We are looking at introducing weekly capping on Oyster when the current technology can be updated.
“This is a complex process as it requires changes not only to the card readers but also to our back office and retailing systems.”