A total of 40 teams will contest the league divided into four groups, Eteläinen (Southern), Pohjoinen (Northern), Läntinen (Western) and Itäinen (Eastern). 29 returning from the 2014 season, two relegated from Ykkönen and nine promoted from Kolmonen. The champion of each group will qualify to promotion matches to decide which two teams get promoted to the Ykkönen. The bottom three teams in each group and the worst seventh-placed will qualify directly for relegation to Kolmonen. Each team will play a total of 27 matches, playing three times against each team of its group.