The Ministry of Transport has admitted it made a$182.6 million accounting error in 2010.
But a spokesperson for the ministry says no funds were mis-spent as a result.
The error meant that almost $183 million of expenditure in the National Land Transport Fund, which funds Transport Agency projects, went undetected when a figure was not carried over between spreadsheets.
That meant the ministry thought it had more money available to spend than it actually did.
A spokesperson says once the error was found, the ministry and the Transport Agency reviewed systems to ensure something similar will not happen again.