The 2015–16 Slovenian Third League began on 22 August 2015 and ended on 29 May 2016[1][2] with playoffs being played on 4 and 8 June 2016.
The 2015–16 Slovenian Third League was divided into four regional groups with a total of 52 participating clubs.
The winners of the regular season in each group played a promotional two-legged play-offs to decide which two teams promoted to the Slovenian Second League.
Reserve teams of the top division sides were ineligible to promote to the second division, due to the rules of the Football Association of Slovenia, which stipulated that one club's main squad and their reserve team must be at least two leagues apart in the country's football pyramid.
[3] A two-legged play-offs between the group winners for promotion to the Slovenian Second League.