Why is the date 1st July 2000 significant to Australians?

So important to Australians that being an Aussie I got it wrong, so it goes to show just cos it's written down doesn't mean it's well known,. or all that important.. How bout putting a year with that date, or putting an answer saying something along the lines about 1st of July being the end of the financial year for a majority of Australians.