The main website for people dealing with the Tax Office and federal social security agencies is down, stopping taxpayers lodging their tax returns.
MyGov, the Commonwealth's hub for its online services, is unavailable for people trying to access their payment summaries and Medicare statements, or deal with Centrelink and the Child Support agency.
The website's operators told Twitter users asking about the outage it was down because of "technical difficulties".
The outage has hit in a week the Australian Taxation Office began diverting staff from their regular work to cope with an unprecedented surge in calls, and more than one million taxpayers lodged their returns.
Hi there, thanks for letting us know. There are currently some technical difficulties, including some people not being able to access myGov. We are urgently investigating the issue and we’re working hard to fix this as quickly as possible. We apologise for any inconvenience.— myGov (@myGovau) July 12, 2019
Changes to the payroll system are directing more taxpayers to MyGov this year, as those working for a business with more than 20 employees will no longer be supplied with a payment summary, and must log on to the website to get the document.
Hundreds of thousands of people lodged a tax return in the first days of tax time this year after the Coalition's boost to refunds for low- and middle-income earners passed the Federal Parliament.
Read more: The changes to taxes and costs from July 1
The Tax Office told clients on Friday morning online portals were down for taxpayers trying to lodge their returns.
A spokeswoman for the Department of Human Services, the agency overseeing MyGov, said some services were unavailable or experiencing slowness but did not say when the outage would end.
"The department is working on the issue and apologises for the inconvenience," she said.
MyGov said on Twitter customers were unable to access Centrelink, Child Support and Medicare online accounts and the Express Plus Centrelink, Child Support and Medicare mobile apps.