A report into a job evaluation scheme run by NI's education and library boards has revealed it cost at least £124m and was not complete 12 years on.
The evaluation scheme cost more than £124m
The Audit Office study criticised the length of time the evaluation had lasted and listed its failures.
It said the scheme resulted in higher pay for more people than anticipated and caused financial problems for the Belfast and South Eastern boards.
The total cost of the scheme has yet to be ascertained.
However, Comptroller and Auditor General John Dowdall said he had identified £124m which had been handed over by the Department of Education and Department of Culture, Arts and Leisure.
Mr Dowdall said he was not able to quantify how much more had been absorbed by the boards within their running costs.
The report said as of 31 July 2006 a total of 28,715 posts in the five boards had been evaluated, but a further 1,795 were outstanding, while some 6,800 classroom assistants whose posts were included in those evaluated had yet to agree their claim with management.
While there were a number of factors which impacted on the completion of the job evaluation exercise "the timescale has been far too long", said the report.
It added: "Northern Ireland Audit Office considers that the exercise should have been managed from the outset within an agreed timeframe, with clear lines of responsibility established for completion within that time frame."
The failure to implement from the outset key recommendations of an agreed action plan - including the establishment of a centralised unit to oversee the scheme - was "a missed opportunity".
That missed opportunity was recognised following an internal management review in 1997, but the necessary steps to rectify matters were not taken for another two years, it added.