MPs and staffers will likely begin moving out of their Bowen House offices over the next six months, so the building can undergo earthquake strengthening work.
Parliamentary Service has now received a Detailed Seismic Assessment which confirms the 22-storey building on Lambton Quay has a 40 percent New Building Standard rating.
Buildings that meet less than 34 percent of the standard are considered a risk to life in a moderate quake and most government departments won't tenant a building that's under 67 percent.
Speaker Trevor Mallard said while the building was not earthquake prone, and no mandatory work was required, the building would be vacated in a controlled, managed way, to enable strengthening work to take place.
Ministers' and MPs' offices will be relocated within the Parliamentary precinct while other affected staff will likely be temporarily relocated somewhere near Parliament.
A range of possible buildings nearby are being actively investigated, to ensure they have a suitable NBS rating.