The start of the League 1 campaign has been put back until the weekend of May 8-9, allowing each team to play the other nine twice in an 18-round season before a play-off series.
Details of promotion and relegation mechanisms between the divisions will be discussed and finalised at a meeting of clubs early next month ahead of fixtures for the Championship and League 1 being published.
The first round of the 2021 Challenge Cup, featuring all 13 UK clubs from the Championship and three from League 1, will take place in March.
Given the unique circumstances of 2021 and such a lengthy period between the early Challenge Cup rounds and the start of the league seasons, entry to the Challenge Cup was made optional for the 10 League 1 clubs, with the RFL stressing the importance of public health and financial considerations.
The majority of League 1 clubs remained keen to enter, including Crusaders, but that would have required an additional preliminary round on March 14, leading to the withdrawal of North Wales and all other clubs bar Barrow, Keighley and West Wales, who will now complete a first round of 16 clubs.
Crusaders chief executive Andy Moulsdale said: “As much as we wanted to take part in this year’s Challenge Cup, we felt the timing of the competition wasn’t right for us. Having consulted with coaches and medical staff, we decided it would mean returning to contact training too soon.
“The lads have been without serious training as a group for the best part of ten months so it’s important we look after them on their return to training.
“We’ll set up Zoom calls in the coming weeks for fans and I’d encourage as many people as possible to join so we can give you more information on the coming season.”