The Department for Education has confirmed in a letter to Darlington MP Jenny Chapman that the Mowden Hall site in the town will close.
The decision is part of a review of buildings used by the department. It is expected that staff will be relocated to new site in Darlington or Newcastle.
More top news
Emma Jesson brings you Saturday night's forecast
Teaching Assistants have marched through Durham in a dispute over pay. They claim council plans could cost them thousands of pounds.
A team of amateur rowers in Durham say they are lucky to be alive after a heavy object was hurled from a bridge, destroying their boat.