The Times reports that the figure was nearer £800m when “off payroll” staff were included – at the same time £287m was spent on staff redundancies.
Minister Francis Maude pledged to ban the use of consultants in some areas without his express agreement.
The government said it had reduced the use of consultants but specialists were still needed for certain projects.
It reports that, despite a pledge to cut back on the use of management consultants, KPMG, PWC, Deloitte and Ernst & Young are now being asked back by the government so major projects like Universal Credit and HS2 are finished before the 2015 general election.
The Cabinet Office figures show £506m was spent on “consultancy and contingent labour” in 2012/13 at the 17 main central departments, while more than £328m was spent on “off-payroll” interim and short-term staff. While the Cabinet Office said there was some “significant overlap” between the figures – other departments denied duplication.
The figures cover a period when £287m was spent on redundancy payments to tens of thousands of civil servants.
The Ministry of Justice spent the most on redundancies, £88.7m, while the Department for Work and Pensions paid out £66.5m.
In 2011, Cabinet Office Minister Mr Maude said government had too often “defaulted into a comfort zone of hiring external consultants to run any kind of complex procurements” and said the government “now forbid the use of consultants in central government procurements without my express agreement”.
A Cabinet Office spokeswoman said the government had put in “stringent controls” on the amount spent on consultants and had spent £1.6bn less in 2011-12 than had been spent on consultants in 2009-10.
But she said: “Cabinet Office delivers projects across a wide range of high-profile policy areas. It is sometimes necessary to recruit for specialist business-critical roles.
“Such roles are only authorised where the skills are not readily available within civil service and where using temporary labour is better value for taxpayers' money than hiring full-time staff.”