Format
The Primera B Nacional tournament had several formats during its history. Since the 2007/08 the competition format follows the usual double round-robin format. During the course of a season, which usually lasts from August to May, each club plays every other club twice, once at home and once away, for a total of 38 games. Teams receive three points for a win, one point for a draw, and no points for a loss. Teams are ranked by total points, with the highest-ranked club at the end of the season crowned champion. In the current format, both the champion and the runner-up are automatically promoted to Primera División. The two other possible spots go to the 3rd and 4th best placed teams, which have to face two Primera División teams in home and away playoff matches, referred to as promotion matches. Tie goes to best placed teams (ventaja deportiva), i.e. to Primera División teams.
The two Primera División teams playing the promotion matches are the 18th and 17th placed teams of a relegation table, calculated by using a three-year-average points system. The 18th placed team faces the 3rd placed team of Primera B Nacional; the 17th placed team faces the 4th.
Before this system was in place, the champions of both second division tournaments would face each other to determine the first promotion. Winner would be promoted and the loser would face the best placed team of the general standing, combining both second division tournaments. Winner would be promoted and the loser would face the 18th placed team of the relegation table. The last team, which would face the 17th placed team of the relegation table, was determined from the four best placed teams according to the general standing (taking out the best-placed team and the two champions). These four teams would face each other in a series of home and away playoff matches (semi-final and final) with ventaja deportiva. Winner would face the 17th placed team of the relegation table.
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