The campaign will run until May 29, 2021 with play-offs in June, subject to Football Association approval.
FC Halifax Town definitely will be in the National League next season, while York City, Guiseley, Bradford (Park Avenue) and Farsley Celtic will compete in the National League North.
Some supporters will be allowed to attend games but stadium capacities will be “significantly reduced from normal levels” and will depend on the design and layout of each ground.
In a letter to clubs, National League chief executive, Mike Tattersall, said: "In terms of crowd numbers, it is likely that ground capacities will be significantly reduced from normal levels.
"The ‘socially distanced’ capacity for each stadium will vary according to the design, layout and configuration of each ground, and will need to be assessed by each club in compliance with government guidance and in conjunction with their local authority."
Clubs voted to end the 2019-20 regular season early in April, just over a month after fixtures were suspended because of the coronavirus pandemic.
Prime Minister Boris Johnson said earlier this month that spectators could be able to return to stadiums from October, with several pilots taking place at various sporting events in the interim.