The 2021 Challenge cup will start in early March, but without amateur clubs because of ongoing Covid-19 complications, the Rugby Football League has confirmed.
League One sides, plus Newcastle, Oldham, Whitehaven and Dewsbury will kick off round one, drawn on 4 January.
Ten remaining Championship sides arrive in round two, while 12 Super League clubs form the last 16 in round four.
The final is at Wembley on Saturday, July 17, with the semi-finals in June.
Championship side Toulouse Olympique will not compete in the competition.
In addition, the four Championship or League One clubs to reach the last 16 of the competition with the entry of the 12 top flight teams, will also qualify for the semi-finals of the 1895 Cup.
That final, last won by Sheffield Eagles in 2019, will take place on Challenge Cup final day, as an anticipated precursor.
Championship clubs will begin their season on the weekend of 27-28 February, after details were confirmed at a virtual meeting.
This 26-round campaign will provide the first fixtures in 11 months for the 14 clubs, which lead to a play-off for the top-six clubs and a '£1m Game' promotion final to decide the champions.
The league table will be subject to a points percentage system as applied in Super League last season, to offset the potential impact of coronavirus on the fixture schedule.
League One's start date will be decided in the new year, as will the play-off system to decide promotion and relegation, but the 18-round, 10 team competition has been formalised.
Fixtures for both leagues will also be confirmed next month.