The Electoral Commission says it will not be taking any action against the Labour Party for failing to immediately disclose a donation worth more than $430,000.
Documents released by the Electoral Commission show the party received the sum from the estate of Brian Dalley in four instalments between April and July 2012.
The electoral law requires donations of more than $30,000 to be filed within 10 working days, but Labour only declared the donation on Thursday, 9 May.
Labour Party secretary Tim Barnett said it did not realise a bequest was actually classified as a donation and therefore had to be immediately declared to the commission.
Mr Barnett said it was an honest mistake, with the party having not received a bequest since new laws were introduced.
He said the party has changed its financial processes to make sure it declares any future bequests within 10 working days.
The Electoral Commission has accepted it was a mistake and said it does not intend to take any further action.