The three and four-storey development will replace the worn out Second World War buildings.
Contractors are moving services such as water, electricity and gas as part of the enabling works ahead of the main construction work, which is due to start in November.
The new block, to be built in two phases, will include operating theatres, four 28-bed wards featuring single en suite rooms, critical care services, intensive treatment and high dependency units, clinical work stations and replacement car parking.
Chief executive Jo Cubbon said: “This is a fantastic development.
“We all know how important it is to replace our 1940s buildings with this new ward block.
“We are working hard to make sure that nothing delays this crucial development for us and the people of Somerset.”
Health chiefs were keen to press on with the development despite current financial restraints.
In a report to planners earlier this year, they stressed the need to replace the old buildings, which have “reached the end of their useful life and are no longer suitable to providing modern healthcare facilities”.
Taunton Deane MP Jeremy Browne, who campaigned for the new facility, said: “The existing facilities are inadequate and there is an urgent need for a modern building.
“I am pleased to note that work has begun and Taunton Deane residents will gain a modern, up-to-date surgical centre.”