About 1,100 staff could be affected by the move but the county council has insisted that it wants to find replacement premises in the County Town.
The county council has been based at Sessions House, a Grade II listed building since 1888.
It is mainly the offices for administration staff but is also where county councillors have their meetings.
Yearly running costs for maintaining the building are around £2 million.
In an internal memo, staff have been told: "Following recent updates regarding the management of our office buildings, and looking at the way that we work, we are currently looking at the future of Sessions House and how we use the other buildings that are part of our strategic headquarters in the future.”
The memo says KCC is committed to Maidstone as the county town and to being a continuing presence in the town.
It adds: “However, as many of you know County Hall is a vast, historic building which has become increasingly expensive and environmentally inefficient to maintain. In its current form, it also limits our ability to make the most of the technology that we have available, and provide our staff with a modern workspace fit for delivering our services in the best way.”
It says the council is in “the early stages of discussions with Maidstone Borough Council about the future use of Sessions House. We will be considering a move to more modern premises and over the next few weeks we will be working with management teams to look at all the options available.”
County Hall was designed by Sir Robert Smirke in the Greek Revival style, and was initially used as a court.
However, after the creation of county councils, it became the offices of KCC and has remained so for more than a century.
In a statement, KCC said: “County Hall in Maidstone has been the home of Kent County Council since 1888 and has served the authority well. However, anyone who has visited County Hall will know that it is a vast, historic building which has become increasingly expensive to maintain. It is also environmentally inefficient and hinders the council’s ability to harness the benefits of technology.
“Occupying grand and costly premises does not help our staff to deliver modern and efficient services and is increasingly at odds with our determination to provide value for money for residents. Our Five-Year Plan commits the council to a greener, leaner and more efficient future and we confirm that we are in the very early stages of considering a move to more compact and suitable premises. This would significantly reduce running costs, help us meet our environmental commitments and offer far better value to Kent taxpayers.
“We have not yet identified new premises but we are committed to keeping a significant presence in the county town of Maidstone and over the coming months we will be considering the needs of staff, residents and visitors to explore the opportunities. Our management teams will be working with staff to develop a set of business requirements for our services to ensure we deliver the new working environment they need and deserve.
“Our ultimate aim is to reduce costs, provide a modern workplace for our staff to make the most of the technology available to us. At the heart of everything is a desire to meet our commitment to Kent’s residents and businesses and deliver on our important environmental aspiration."
As the headquarters for one of the largest councils in the country, Sessions House is a landmark building in the county.
It is an impressive building and the architect who designed it also designed a string of other well-known buildings, including the Royal Mint in London and the Royal Opera House.
But the costs of maintaining it are considerable and over time, those costs have increased and KCC has decided the time is right to cast around for a new home.
Its emphasis on retaining its presence in Maidstone offers a degree of assurance that it is not looking for an out-of-town equivalent of a retail park.
The question is whether there are alternative premises that fit the bill: it is not just office space that is needed but a building that can accommodate a council chamber for up to 80 councillors.
And who might be interested in acquiring it? Developers might see an opportunity to convert it into some kind of luxury residential scheme but the costs of that would be considerable.