Ministers have given the green light to refurbish Morier House on Halkett Place.
The States office block opened in 1998 and is currently home to the States Assembly's administrative support service, the States Greffe.
Work will include creating a dedicated space for States Members - so those who are not Ministers have an official workspace.
We're told a funding bid will be made for 2021, but although a sum has been earmarked, it won't be made public until a contractor is chosen.
Jersey's Chief Minister, Senator John Le Fondré, tells Channel 103 the work needs doing:
"Even though it's not that old a building, there are aspects in there which have deteriorated - like air conditioning - to the extent that actually the fabric of the building can become damaged."
It comes as the Government of Jersey also announced plans to spend £600,000 to investigate moving to a single central office block.