All eighteen First-class counties competed in the tournament which ran from the end of April with the final taking place at Lord's on 1 July.
[3] The 2017 competition was moved earlier in the season with a reduced knockout stage in order to allow the 2017 NatWest t20 Blast to take place during the school summer holidays and England players to prepare for the 2017 ICC Champions Trophy taking place in England and Wales during June.
[1] The scheduling of the competition earlier during the domestic season was also designed to allow limited overs cricket to be played in two blocks - one for the One Day Cup and one for the T20 Blast.
The knock-out stages of the competition resumed towards the end of the Champions Trophy with the final taking place at Lord's on 1 July.
[1] As part of their punishment for accepting a £3.8 million financial aid package from the ECB during the 2016 season, Durham began the 2017 competition with a deduction of two points.