The decision to extend daylight saving in south-eastern Australia could create a mini-Y2K by putting the internal clocks on computers, smartphones and corporate servers out of sync.

From this year on, daylight saving in NSW, Victoria, ACT, Tasmania and South Australia will end a week later than usual on the first Sunday in April and, with the exception of Tasmania, recommence three weeks earlier on the first Sunday in October.

The change was intended to harmonise daylight saving dates across the country and give Australians more daylight hours, which in turn benefits the environment by reducing evening electricity use.

Many electronic devices with internal clocks are set to adjust automatically for daylight saving but, as a result of the recent date changes, the adjustments this year will be incorrect.

The fallout for regular consumers could include missed meetings or appointments, but corporations face bigger headaches as their internal servers, fleets of BlackBerry devices and automated systems such as payroll, stock trading and manufacturing are operating under the old daylight saving regime.

Clocks must therefore be adjusted manually or via software updates from the device makers.

A similar issue occurred in the United States last year when daylight saving was changed to kick in three weeks earlier and end a week later. At the time The New York Times reported it would cost public companies $US350 million to make computer fixes to deal with the changes.

Microsoft has issued an advisory to users of its Windows, Outlook and Windows Mobile products recommending they download an update from that will synchronise computer clocks with the daylight saving changes.

"The synchronisation [issue] is not exclusive to Microsoft products. It affects all devices that update automatically according to the old daylight saving schedule," Microsoft's customer and partner experience director, Hugh Jones, said.

IDC analyst Liam Gunson said widespread problems could occur if people were not made aware of the issue and did not take action to fix it.

He said the same problems were predicted in New Zealand last year when daylight saving changes were made but no serious problems eventuated.

"It was really just a matter of education and people knowing that they need to download a certain patch or look at their IT systems and it appears that most people did," he said.

The issue has been likened to the Y2K or millennium bug, albeit on a far smaller scale and with less serious consequences.

Y2K caused chaos leading into the new millennium as it was feared computer systems, which stored years as only two digits, would be unable to recognise dates from 2000 onwards.

Governments spent hundreds of billions of dollars working to fix the problem, with computer engineers predicting doomsday scenarios such as that critical finance and electricity industries would stop operating and planes would fall out of the sky.

However, when the year 2000 finally arrived, there were no major computer disasters. There is debate over whether this was a result of the immense preparation for Y2K or people overstating the seriousness of the problem.