It has been nearly a year since councillors signed off the proposal to refurbish and reconfigure Shirehall in Shrewsbury at a cost of £24 million.
The authority said work to turn it into a 'public sector hub' would be completed by autumn 2021, however, little progress has been made.
It had expected a final business case, developed designs and a project budget would be presented to cabinet in early 2019 for approval.
However, Clive Wright, chief executive of Shropshire council, said the authority must balance the budget pressures with the need to transform Shirehall.
Earlier this month the council implemented a spending freeze until the end of the year after confirming it is facing a £6 million overspend.
Mr Wright said: "At a meeting of the full council in December 2018 councillors agreed to proceed with the next stage of plans to refurbish and reconfigure Shirehall and turn it into a ‘public sector hub’ that will see the building become home to not just Shropshire Council but also to a number of public sector partners – while also providing opportunities for private sector businesses.
"Mindful of the balance between pressures on budgets and the need to make savings, with our need to transform our workspace and workforce and the shared benefits of collaborating with partners, work has continued on testing the business case and fine tuning our requirements."
The report that went before councillors last year said the current building is old fashioned, unwelcoming and disorientating for staff and visitors alike.
Although the building is structurally sound and its key mechanical and electrical systems remain viable, a number of years with minimal planned maintenance has had a negative impact on the quality and performance of the building, which now needs to be addressed.
A number of key elements have exceeded their expected lifespan, the council said.
The overall cost of the project is estimated to be £24.1m, but this spend was due to be met by the proposed income generation and savings, with a return of seven per cent anticipated.
The work will be funded from Shropshire Council’s capital budget which is money that legally can only be spent on or invested in assets and infrastructure projects, and not on the direct provision of council services.