Gallagher Premiership players will have guaranteed in-season breaks under a new structure for the three domestic seasons from 2019/20.
The changes, announced by the Rugby Football Union, Premiership Rugby and the Rugby Players' Association, also include a maximum 35 match involvements in a season and a mandatory five-week post-season rest for all players.
Meanwhile, the Premiership will end in late June and summer tours, previously held in June, will take place in July.
Rugby Football Union chief executive Stephen Brown said in a statement the new structure was a partnership between the RFU, Premiership Rugby and the Rugby Players' Association and that it had focused "on the requirements of player welfare".
Premiership Rugby chief executive Mark McCafferty said the structure achieved "a number of progressive goals for the English structure over the next three seasons, building in new player management approaches, reducing overlaps and scheduling more of Gallagher Premiership Rugby for the better weather conditions of spring and early summer".
RPA chief executive Damian Hopley said: "It is fundamental that players had their say in the shaping of this new season structure" and added that the new agreement "gives players guaranteed in-season breaks for the first time and reduces playing thresholds".
Twickenham will host the finals on June 20, 26 and 18 for the years 2020-22 with the campaigns starting on October 20, September 12 and September 18 respectively.