2000 Tercera División play-offs
The 2000 Tercera División play-offs to Segunda División B from Tercera División were the final playoffs for the promotion from 1999–2000 Tercera División to 2000–01 Segunda División B. The first four teams in each group took part in the play-off.
Format
The 68 participating teams were divided into 5 series each made up of 4 groups in the category, with the exception of Series E , which was only formed by Group XII . Each series was divided into 4 groups formed by a 1st, a 2nd, a 3rd and a 4th classified from each group, which played a double-round playoff. Each victory was equivalent to 3 points, the tie to 1 point and the defeat to 0 points. The champion of each group obtained the promotion to Second Division B.The distribution of each series was as follows:
Teams for 1999–2000 Play-Offs
Group I – Galicia  | Group II – Asturias  | Group III – Cantabria  | Group IV – Basque Country  | Group V – Catalonia  |
| 1st Celta de Vigo B | 1st CD Lealtad | 1st SD Noja | 1st Real Sociedad B | 1st CF Balaguer |
| 2nd Deportivo La Coruña B | 2nd Club Siero | 2nd CD Tropezón | 2nd SD Lemona | 2nd RCD Espanyol B |
| 3rd UD Xove Lago | 3rd Club Marino de Luanco | 3rd Racing de Santander B | 3rd Arenas de Getxo | 3rd CE Mataró |
| 4th CD Lalín | 4th AD Universidad de Oviedo | 4th CD Miengo | 4th SD Eibar B | 4th UE Cornellà |
Group XI – Balearic Islands  | Group XII – Canary Islands  | Group XIII – Region of Murcia  | Group XIV – Extremadura  | Group XV – Navarre and La Rioja   |
| 1st CD Atlético Baleares | 1st UD Las Palmas B | 1st Club Olímpico de Totana | 1st Mérida Promesas UD | 1st Peña Sport FC |
| 2nd CD Constancia | 2nd UD Orotava | 2nd UD Horadada | 2nd CD Don Benito | 2nd UDC Chantrea |
| 3rd CD Manacor | 3rd UD Vecindario | 3rd AD Mar Menor | 3rd UP Plasencia | 3rd CD Mirandés |
| 4th SCR Peña Deportiva | 4th Castillo CF | 4th Orihuela CF | 4th CF Villanovense | 4th CD Logroñés B |