Due to the COVID-19 pandemic in Portugal, no teams were relegated on the previous season, and a total of eight teams from 2019–20 Campeonato Nacional II Divisão first stage series were promoted, one from each serie.
Promoted from Campeonato Nacional II Divisão The new competition format consists of two stages.
[2] In the first stage, the 20 clubs will be divided in two series (North and South) of 10 teams, according to geographic criteria.
On the championship group, all eight teams play against each other in a home-and-away double round-robin system, to decide the champions.
First Stage schedule was drawn on 28 August 2020 at FPF headquarters, and was originally set to be played from 27 September to 6 December 2020 but, due to restrictions imposed in response to the COVID-19 pandemic in Portugal, was concluded on 13 January 2021.