Wellington's Asteron building will be closed for two weeks, a spokesperson for its largest tenant Inland Revenue (IRD) says.
The 17-storey building was evacuated on Wednesday when an engineer found faults in the stairwell. It was a result of last week's magnitude-7.8 earthquake.
Over 2000 IRD staff work in the building, but Communications Adviser Rowan Macarthur says no frontline services have been affected, call centres are running as normal as they operate from a separate building, and all payment systems are operating.
Building owner Mark Dunajtschik says the claims that the building is structurally unsafe have been blown out of proportion.
IRD staff were sent home on Wednesday due to concerns about cracks in the stairwell (supplied)
"The main part of the building is perfectly sound and safe" he says, "The perceived danger is exclusively concentrated into the stairway on one wall".
Mr Dunajtschik says the cracks are not new, they were there after the 2013 earthquake and have now reappeared.
He says there's a disagreement between the engineers who checked the building.
"We have two professional opinions and they don't concur with each other - the management has decided to err on the side of caution".
He says that remedial work is being undertaken to address the concerns of the engineer who believes the building is unsafe.
IRD staff who can work offsite are doing so, whether from home or cafes.