2020–21 Segunda División B

The 2020–21 Segunda División B season was the 44th since its establishment and the last as the third tier. A total of 102 teams participated, and were distributed in three groups of 20 teams each and two groups of 21, with eight subgroups of ten teams each and two with eleven teams each. On 6 May 2020, the Royal Spanish Football Federation announced the expansion of the league to what were initially five groups of 20 teams each for the 2020–21 season due to promotion from the Tercera División groups in the curtailed past season being applied.

2020–21 Segunda División B

The 2020–21 Segunda División B season was the 44th since its establishment and the last as the third tier. A total of 102 teams participated, and were distributed in three groups of 20 teams each and two groups of 21, with eight subgroups of ten teams each and two with eleven teams each. On 6 May 2020, the Royal Spanish Football Federation announced the expansion of the league to what were initially five groups of 20 teams each for the 2020–21 season due to promotion from the Tercera División groups in the curtailed past season being applied.