It is the second tier outside the top two professional leagues, the Primera División (also known as La Liga) and Segunda División (also known as La Liga 2), being behind Primera Federación and above Tercera Federación.

On 6 May 2020, the RFEF announced the creation of a new, two-group, 40-team third division called Primera División RFEF, which resulted in the former third division, Segunda División B, dropping down a level and becoming Segunda División RFEF; the changes were made effective for the 2021–22 campaign.

[4] Segunda Federación features 90 teams divided into 5 groups of 18.

The champions of each group achieve automatic promotion to Primera Federación, while the other top four teams qualify for a play-off round, where five of the 20 teams qualified also achieve promotion.

The bottom five teams in each group are relegated to the Tercera Federación.