PricewaterhouseCoopers (PwC) is planning a £80m revamp of its central London headquarters.
Premier Property Group has submitted plans to rebuild the Plumtree Court site, more than doubling its size to 412,000 sq ft. Its current floor space is 200,000 sq ft.
Under the plans, PwC would decant from the building to other central London offices when its lease expires in December 2011.
PPG originally won planning permission in 2008 to refurbish the building, but has since opted for a new-build development.
The 10-storey scheme will have a construction cost of around £80m, and will feature trading floors on the lower levels to attract banking tenants.
It is the first major planning application submitted for a 'Midtown' development in London since the recession.