The 2015–16 season was Colchester United's 79th season in their history and their eighth consecutive season in League One, the third tier of English football. Along with competing in League One, the club will also participate in the FA Cup, League Cup and Football League Trophy. The club suffered relegation to League Two, the fourth tier of English football, for the first time in 18-years after finishing the season in 23rd position and in the relegation zone. Colchester made an early exit in the League Cup at the hands of Reading, while they made the fourth round of the FA Cup for the first time in ten years but were defeated by Premier League side Tottenham Hotspur 4–1.