11 and 13
BBC Sources have indicated that next year’s series of Doctor Who, the first with the thirteenth Doctor, will be broadcast in the Autumn of 2018.
New showrunner Chris Chibnall is currently still working on season three of his ITV crime drama Broadchurch , which is currently being edited and will premiere in the UK on 27 February.
Chibnall told RadioTimes.com that he has not yet been able to fully dedicate himself to Doctor Who. After finishing work on Broadchurch he intends to take a holiday before launching into Doctor Who.
Chibnall will lead the team searching for the new Doctor, although the choice will need to be agreed by the BBC director of content Charlotte Moore and head of drama and former Doctor Who Executive Producer Piers Wenger. It is expected that a new Doctor will not be announced before the Autumn, with the new Doctor making their debut at the end of the 2017 Christmas Special.
Sources told RadioTimes that the first Chibnall series will begin filming at the start of 2018 for transmission in the Autumn.
Series 10 of Doctor Who, the last full series starring Peter Capaldi. is currently in production and will begin transmission on 15th April.