The plush new surrounds of 1 William Street have added $50 million to Queensland taxpayers' rental bill for the 5000 public servants who worked in the building.

The state government will pay $223.14 million in overall rent for all government buildings in the CBD by June 30 next year, including the $56 million it cost to rent the 75,419 square metres at 1 William Street, the so-called "Tower of Power".

This overall office space rent had increased from $173.29 million in 2015-16, before the 5000 public servants moved into 1 William Street in October 2016, but will increase to $223.14 million by June 2018 when I William Street is included and rent in older buildings is removed.

Rent in 1 William Street is far more expensive than the rent paid for other buildings which the state government has leased to house public servants, because it is a modern, state of the art building.