TfL have announced that Kennington will be moved from zone 2 to the boundary of zones 1 and 2 from next Sunday, May 16th. The move is necessary to enable the new zone 1 stations at Nine Elms and Battersea Power Station to be connected to the rest of zone 1. The Northern line extension is on target to open later this year.
No fares will increase as a result of this change*. Passengers arriving from the south will still be charged up to zone 2, while those arriving from zone 1 will be charged the zone 1 only fare instead of the old zone 1-2 fare. Kennington to Elephant & Castle is the oddity as both stations are dual zoned with the boundary running along the line between them. In keeping with the no fares are increased pledge, this will still be charged as a zone 2 fare.
*Actually a small but significant number will. Railcard holders travelling from Kennington to other zone 1 stations between 1600-1900 will now pay the full £2.40 single rather than the discounted £1.60 as the evening peak into zone 1 discount only applies if you start outside zone 1.
Note: The contents of this post have been updated following receipt of the official TfL press release. The original post mentioned that the fare finder data had been updated on May 6th in error; this was corrected on May 11th.