The showrunner admitted that he is nearer the end of his time on the show than he is the beginning, Entertainment Weekly reports.
The 51-year-old took over as show boss following Russell T Davies's five-year run, with Moffat's first series in charge airing in 2010.
Saying that "statistically... [he is] nearer the end than the beginning" of his time as showrunner, Moffat added: "I just take it a year at a time. I think the feeling of it being done for you is quite unambiguous when it suddenly arrives."
Moffat's comments follow suggestions this week - played down by the BCC - that actor Matt Smith will leave the show in this year's festive episode.
Photo gallery - Doctor Who series 7B posters:
John Barrowman sparked rumours that he will reprise his role as Captain Jack Harkness during an interview with ITV's This Morning last month. However, he later backtracked on his comments.
Moffat has insisted that the 50th anniversary episode should not simply be turned into a "fanfest", adding: "We can't make this all about looking backwards. It's actually got to be the start of a new story."
Doctor Who returns to screens for a new series next Saturday (March 30) at 6.15pm, with a prequel to first episode 'The Bells of Saint John' having been unveiled today (March 23).
Watch the stars of Doctor Who speak with Digital Spy below: