The 35-year-old batting maestro has held the top job for the past 10 years but has decided to relinquish the role.
He is in the twilight of his career and is still weighing up whether he will return next summer.
"I need to look at what is best for my family," Cumming said.
"I'll do that in the next month or so, but I still thoroughly enjoy playing. There is probably a very good chance I will be playing again, but I will need to look at how the season is structured. But if I play, I won't be captaining."
Cumming let the Otago team know during the Plunket Shield match against Wellington in Queenstown this week but said he made the decision a week earlier. He felt is was the right time to step down.
"I've been in the role for 10 years and you want to make sure guys are still motivated and listening to what you say. It is also important for Otago cricket, because if they want to move forward there are some things that need to change to make the team successful."
Former test opener Aaron Redmond, Black Caps all-rounder Nathan McCullum and wicketkeeper-batsman Derek de Boorder have all captained Otago and shape as the leading contenders.
Cumming led Otago in 69 first-class matches but the team enjoyed greater success in limited-overs cricket during his reign. The Volts won the one-day competition in 2007-08 and the following season won the twenty/20 tournament.
Coach Mike Hesson has also signalled his intention to move on after six years in the job.
