The long-awaited community access point based at Bourne Corn Exchange will open to the public from 9am on Thursday.
The building will be a one-stop-shop for services in the town housing the town, district and county councils, as well as the library and register office.
Leader of Lincolnshire County Council, Martin Hill said: “It’s great that after so much hard work, the community access point is almost complete.
“It will put local services at the heart of the community and by sharing space with the district council we’re saving taxpayers money.”
“Importantly, the move will give the library a new lease of life, with longer opening hours and better parking, making it easier to visit at a time that’s convenient for you.”
The new library, while slightly smaller than the current facility in South Street, will provide longer opening hours on Tuesdays, Thursdays and Saturday mornings.
South Kesteven District Council leader Linda Neal said: “The building is fantastic and I am pleased with the end result.
“There has been a lot of hard work to get us to this point, but I am sure that the town’s residents will feel that this is a project that has been worth doing as it has ensured the future of some of the town’s key facilities.”
About 40 staff from South Kesteven District Council, most of whom are currently based in Grantham, and Bourne Town Council are in the process of moving into offices created on the first floor.
Many moved in last week to get up to speed for the public on Thursday.
Building work on the £600,000 project, by contractor Burmor Construction, started in April 2012 and continued until the end of February.