Following a break to ease fixture congestion caused by the 2015 Rugby World Cup, the three-team play-off held in 2015–16 was expanded, and a four-team format was announced.
[1][2] The play-off comprised 3 matches, contested by one team from the Premiership, one from the Top 14, and two from the Pro14.
The three losing teams all competed in the 2017–18 European Rugby Challenge Cup.
[citation needed] Four teams competed in the play-off, having qualified as either the highest team from each league that did not already qualify for the Champions Cup, or as the winner of the 2016–17 European Rugby Challenge Cup.
[3] The following teams had qualified for the play-off: A draw was held on 15 March 2017 to determine the two semi-final matches.