Plans to redevelop a five-storey HM Revenue & Customs office in the city centre into 70 flats were given the green light on Wednesday.
Preston City Council approved plans submitted in April by Doncaster-based investor Empire Property Concepts, to convert the 39,200 sq ft Charles House at 8 and 8a Winckley Square into apartments.
The current property was built in 1968 to house HMRC, which occupies the building on a 25-year lease from 2003 but intends to vacate the property this year.
It is one of several tax offices across the North West that have been earmarked for closure by Whitehall as part of a strategy to consolidate civil servants in fewer buildings, to cut costs.
The property was put up for sale with Lancashire-based agency Morgan Martin for £4m in April, and Empire Property is thought to be a prospective buyer.
Under its proposals, the residential units would comprise 58 one-bedroom apartments and 12 two-bedroom apartments.
DLP is the planning consultant on the scheme and the architect is SLA Design.