After his parents moved to the small town of Bad Bederkesa in Lower Saxony in 1982, he went to the Lower Saxon "Internatsgymnasium" (boarding school) in Bederkesa, where he took his Abitur in 1989. From 1989 till 1991, McAllister served as a soldier in the Bundeswehr, in Panzerbataillon 74 in Cuxhaven. From 1991–96 he studied law with a scholarship of the Konrad Adenauer Foundation at the University of Hanover. In 1994, McAllister became local chairman of the Junge Union, the CDU youth organisation, in the Cuxhaven district.