The cost of a travelcard was due to rise by 4.1% on 3 January. But the increase has now been delayed – potentially until 19 January.
Transport for London has now confirmed to the London Assembly that they need more time to update their system.
It's a pretty difficult task to update the system that decides what fare to charge someone when they're heading across London's transport network – there's thousands of possible combinations.
The last-minute cap on fares means this update is going to take Transport for London longer than expected to implement, so they won't meet the 3 January deadline.
A TfL representive today told the London Assembly that it typically takes around 30 days to update the organisation's system – and did not deny that, as a result, the fare rise could now be delayed until 19 January. TfL's press office did not respond to requests to confirm this date.
UPDATE: This has now been confirmed by the Mayor's office.
The plus side: this means Londoners will be able to travel at 2013 prices for longer than expected.
But the delay is pretty embarrassing for London's politicians. Here's why it's happened.
Earlier this month Boris Johnson proudly announced the new transport prices as a "real terms freeze".
Two days later, George Osborne blew that work out of the water.
Boris eventually decided to raise fares by the smaller amount. Although this leaves questions about who's going to make up the budget shortfall.
Assembly Member John Biggs said it was a "farcical" situation and said the Mayor should be "knocking on the door of 11 Downing Street demanding the Chancellor cough up that cash".
...while the confusion has also delayed a planned trial of payment by contactless debit cards on the London Underground.
There's a lot of people at TfL who will be unexpectedly working hard over Christmas.
But cheaper travel for the rest of us in those first hungover days of the new year.