In early 2013, Jackson was selected for the England under-19 side to tour South Africa, where he played in both Youth Test matches and three One Day Internationals in a five-match series, as well as in the two-innings warm-up match against a Western Cape Invitation XI.
With Sussex's first-choice wicket-keeper, Matt Prior, on England duty in the 2013 Ashes series and regular back-up Ben Brown injured with a broken finger, Jackson made his competitive debut for the club in a Friends Life t20 match against the Essex Eagles on 21 July 2013. Although he did not bat and Sussex lost by seven wickets, he made an impression by stumping Greg Smith, Hamish Rutherford and Ravi Bopara for Sussex's only wickets of the match. He appeared in a total of six limited overs matches for Sussex in 2013.