After a first successful season in the Master Junior Formula, finishing the season as runner-up, Cortés graduated to Spanish Formula Three Championship in 2006 with Spanish team Escuderia TEC-Auto. A strong third place in the standings in his rookie year boost him as the favorite for the followed season.
Cortés continued with TEC Auto into the 2007 season. During the season he took nine podiums, including six race wins, to win the drivers' title ahead of his teammate Marco Barba, winning the title by just four points.[1]
After only seven races in the championship, Máximo was replaced by Aleix Alcaraz due to financial problems;[4] during his short stint in the championship, Cortés finished two times in the points positions, a seven in Spa being his best result.