The Financial Ombudsman Service spent more than £5m on business consultancies to provide expertise to the organisation last year, a Freedom of Information Act request shows.
The complaints adjudicator used a total of 38 consultancies in the 2015/16 financial year. The highest paid received nearly £3m.
The FOS also employed three individual consultants at a cost of £20,237, of which the highest paid earned £15,407.
The FOS did not disclose the names of the consultancy firms or individual consultants.
The FOS has budgeted slightly less for consultants next year however, the FOIA request shows, at £5.1m compared with the £5.4m that was spent in 2015/16.
A FOS spokeswoman says: “Careful use of consultancy support has helped us make good headway with the efficiencies we’d planned across our wider operations.
“We’re currently consulting on our plans and budget for the next financial year taking into account the ongoing uncertainties about our case load. Bearing this in mind, we continue to try to reduce our support costs, find smarter ways of working and get better deals with our suppliers.”
Earlier this week, the FOS proposed increasing its overall budget for next year by £30m to £295m, up from £265m this year.
Contractor staff costs, which were budgeted at £40m for 2016/17, are set to rise to £70m in 2017/18.
The use of consultants is common in financial services regulation.
The FCA, for example, has also spent more than £1.2 million on projects run by a consultancy firm where former boss Hector Sants is a partner, according to another FOIA request.
The Treasury also spent over £400,000 on contracts awarded to firms for consultation on how to promote new Government backed guidance service Pension Wise before it launched.