Liga TDP

The Liga TDP is Mexico's fourth tier in the Mexican League System. The Liga TDP is divided into 13 groups. For the 2009/2010 season, the format of the tournament has been reorganized to a home and away format, which all teams will play in their respective group. The 14 groups consist of teams who are eligible to play in the liguilla ascenso for two promotion spots, teams who are affiliated with teams in the Liga MX, Liga de Expansión MX and Liga Premier, which are not eligible for promotion but will play that who the better filial team in a sixteen team filial playoff tournament for the entire season.
Teams.
Participating clubs for the 2020–21 tournament:
Group I.
(2020-2021) There are 11 teams in Group 1 (G1). Note: Delfines Márquez was announced as a participant for the season, but was excluded from the league after week 15 for failing to fulfill his obligations as an affiliated club. 
Group II.
(2020-2021) There are 15 teams in Group 2 (G2) 
Group IV.
(2020-2021) There are 19 teams in Group 4 (G4). Note: Promodep Central was enrolled in the season, but the team was retired after week 23.
Group VIII.
(2020-2021) There are 18 teams in Group 8 (G8). Note: Limsoccer F.C. was enrolled in the season, but was expelled after week 6 for failing to fulfill its obligations as an affiliate.
Group XIV.
(2020–2021). There are 7 teams in Group 14 (G14).
Current format.
Tercera División currently features 195 teams divided into 14 groups. There are 23 teams with filials (affiliates) in the Liga MX (First Division), Ascenso MX or Liga Premier, who are not eligible for promotion. The Tercera follows the usual double round-robin format in which each club plays every other club twice within their own group.
The teams will be divided in accordance to their geographical zone. The teams in each subgroup of 13 will then play each other in the double round-robin format within their own subgroup. Teams receive three points for a win, one point for a draw, and no points for a loss. If a game ends in a draw both team are awarded one point for the draw in regulation time and will then move on to the execution of penalties. The team who wins in the penalty series will be awarded a point in addition to the point won for drawing during regulation time. Teams are ranked by total points won.
Qualification for promotion.
Two teams from the Tercera Division will be promoted to Second Division de Mexico, Campeon (Champion) and Subcampéon (runner-up). The champion will be promoted to the Liga Premier Serie A, depending on their economic development and infrastructure, the team could be placed in Serie B in case of failure to comply with the participation requirements of Serie A. The runner-up will play in Serie B.
Of the teams that are eligible for promotion, 64 teams will qualify for play-offs to determine which team will be promoted. The Round of 32, Round of 16, Quarter-finals, Semi-finals and the finals will be played in a home and away format, the winner being determined by the aggregate score. Also, Participating in the play-offs is the 16 affiliate clubs without the right to be promoted to the Liga MX, Ascenso MX and Liga Premier.
Round of 32.
The 64 teams classified to the promotion stage will be divided into two zones of 32 clubs according to their geographical location. Zone A will integrate the teams from groups 1 to 7 of the regular season and Zone B will group the clubs belonging to groups 8 to 13. The teams will be seeded based on their final overall record in regular season play.
Promotion.
The team that wins in the aggregate score will be crowned champion and will be promoted to the Liga Premier. This team will be placed on Serie A or Serie B according to the social, sporting, financial and legal requirements of the Second Division. The runner-up will be promoted to the Serie B.
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Certification requirements.
For Tercera Division Profesional Certificate be considered, you must meet the social, sporting, financial and legal requirements; Clubs who win promotion and get the support settlement letter from the Division to participate in the Segunda Division de Mexico complying with the following: