Newmont Waihi Gold says it will have no work for most of its 100 underground employees for several months next year.
The company says the Trio mine in the Hauraki district is scheduled to finish production in July 2014 and its Correnso underground mine, which was recently granted resource consent, will not be ready to start production until February 2015.
Spokesperson Kit Wilson says during that period, limited work will be available underground.
The company does not know how many workers will be needed until it can make an underground assessment at the end of the year.
Newmont's open pit and its process plant will not be affected by the production gap.
Mr Wilson says delays in obtaining consents have been part of the problem.
He says Newmont has been talking to employees for the past few months and is trying to give them as much notice as possible.
Hauraki mayor John Tregidga says he is disappointed the company has decided it needs to do further exploration before mining at Correnso begins, when he believes it would have had sufficient knowledge of the mineral deposit before applying for resource consent.
He says it is difficult to say what impact the anticipated period of no work will have on the Waihi community.
"This will have an effect on the community. There will be a number of people - experienced people - that may head back overseas to Australia etc," Mr Tregidga says.
"So, yes, I have to say somewhat disappointed."
However, he says the Waihi community is pretty resilient and he is sure they will get through it.
The Engineering, Printing and Manufacturing Union says it is meeting with Newmont Waihi Gold and will be consulting with union members to make sure they are kept informed and any impact is minimised.