Since 1956, the tournament is played between six teams. The teams are Auckland, Wellington, Canterbury, Otago, Central Districts, and Northern Districts. The winner of the tournament is decided based on a round-robin competition.
Each team plays the other team in the league stage. A match win is worth 12 points and no points are awarded for a drawn or lost match. A tie results in both teams getting 6 points each. If a team wins a match that has a playing time of ten hours or less remaining, then that team getting additional 6 points. If a match is tied after both teams bat for only one innings, the teams are given 3 points each.
Bonus points for batting are awarded to teams depending on their score in the first 110 overs of their first innings. If a team reaches 200 runs during this period, they are given 1 point. A second point is awarded at 250 runs, a third at 300 runs and so on.
Bonus points for bowling is given to teams if they take a said number of wickets in the first 110 overs. 1 point for taking 3 wickets, second point at 5 wickets, third point at 7 wickets and fourth point at 9 wickets.
The team with the most points at the end of the round-robin stage is declared the champion. Auckland is the most successful side in the tournament’s history, winning 24 titles. Mathew Sinclair is the most successful batter of the tournament with 9148 runs, whereas Stephen Boock has been the most successful bowler, picking up 399 wickets.