On 30 April 2021, the Royal Spanish Football Federation announced that the play-offs would be played in four locations of Extremadura.
Since the 2021–22 season the promotion will be played in the Primera División RFEF.
The competition for these places is reserved this season for the first three classified from each of the five groups that make up the entire Segunda B, as well as the best fourth classified that was resolved by a final score based on points per game.
It took place in Extremadura, in a concentration format, and consisted of two qualifying rounds in which the matches were determined by drawing lots, pitting those who would have obtained a better classification against those who would have obtained a worse classification, avoiding, as far as possible, that they face each other two teams that would have belonged to the same group.
The remaining clubs were assigned to the Primera División RFEF next season.