In 2021, Argentina's Serie B league will be divided into Group A (high ranking group) and Group B (low ranking group) according to the ranking of last season. Last season, the league was suspended due to the COVID-19 epidemic. The top eight teams of the first two groups were suspended from entering Group A this season, and the remaining teams entered Group B this season. Group A will be divided into two groups for a single round robin competition. The first place in each group will be promoted to the final of the first stage. The winner of the final will participate in the League A next season. Group B is also divided into two groups for a single round robin game. The top two teams in each group, a total of four teams, will participate in the knockout game of the upgrading play off game together with the team that has not been upgraded in Group A in the first stage. The two second place winners in Group A in the first stage will directly enter the third round of the knockout competition. The losers in the final in the first stage will directly enter the semi-final of the knockout competition. The final winner of the knockout competition will be eligible for another League A competition next season.