A registered property valuer by trade, Parkinson took over as CEO from Jim Smillie in January 2011 after earlier working as the rugby development manager in Northland.
"My last day is June 30 so I've still got seven weeks to go. I've been communicating with the board and there'll be a handover process so looking to see out the Blues game [Northland Barbarians v Blues at Toll Stadium] on the 24th June and then I'll depart the following week," he said.
Looking back, Parkinson said he would like to think he has left the union in a better place than when he took charge.
"We've got our economic model under control and we've been in the black in the last four years, so we're now sustainable and that's growing our income and getting our expenses under control."
He dwelt briefly on last year's dismal performance by the Taniwha but said 2015 was "a perfect storm" in and around losing both coaches Derren Witcombe and his assistant George Konia resigning before the then ITM Cup started in August.
The appointment of new coach Richie Harris, loss of 10 key players from 2014 and key injuries all played a part in the team's overall performance, he said.
"It's not about winning games, it's about playing well, playing an exciting brand of Northland rugby and showing that the players want to play for the jersey and be up there."
NRU board chairman Ajit Balasingham said no timeframe has been set on advertising the CEO's position.
"We want to keep the momentum going. We're going into the season and we don't want too many changes at this stage. So Alistair is going to step in, take over the role and then we can decide how we go forward."
Mr Balasingham hailed Parkinson's contribution to Northland rugby and said he would be sorely missed.
"Jeremy's been a great leader for Northland. Since the last five years he's been here, we've done a hell of a lot of work in getting this union to a good position and he's well-respected, not just in Northland, within New Zealand and in other provincial unions."
