Broadland council's HQ - which includes a nuclear bunker - is going on the market.
Earlier this year, Broadland District Council (BDC) agreed to join together with South Norfolk Council and move to the Horizon Centre at Broadland Business Park.
But before BDC can decide what to do with their current building - Thorpe Lodge on Yarmouth Road - it must be advertised for at least 12 months.
How much the building could be sold for has not been revealed.
After 12 months the council can pursue other options for the site.
Anyone purchasing Thorpe Lodge will get a Grade II listed building, complete with a nuclear bunker built in 1989.
A spokesman said the authority must seek the best value for residents and maximise returns.
BDC leader, Shaun Vincent said: “This is a really exciting time for the council and the move to the Horizon Centre will save taxpayers millions of pounds over the coming years.
"It’s forward-looking decisions like these that ensure we can continue to deliver the high standard of services that our residents really value and allow us to keep council tax low in our district."
Mr Vincent said the move to the Horizon Centre would benefit residents, providing financial savings and a reduction in BDC's carbon footprint.
The council leader has previously said he would like to see the building turned into a commercial centre, where parts are let out as a business hub.
One other option Mr Vincent envisaged for the future of Thorpe Lodge was to redevelop it, which could involve demolishing parts of the building.
The decision to move to the Horizon Centre has not had universal support, with opposition councillors opposing the multi-million-pound purchase.
At a meeting in May, Liberal Democrat councillors raised fears about the suitability of the site, whether all the options have been fully considered and whether information was being kept out of the public eye.
This paper challenged the monitoring officer's decision to keep information on noise, energy reduction and accessibility from the public eye.
The Horizon Centre is two miles from the current office.
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