It's a new financial year as of today, and that means anyone in Australia who worked in the last twelve months can submit a tax return. In this wonderful country of ours, you're able to prepare and submit a tax return yourself -- but don't get tricked into downloading dodgy software along the way.
In Australia, we use e-tax to submit personal income tax returns -- although 2015 is the last year that e-tax will exist, since it's being replaced by a newer and shinier piece of online-only software called myTax.
To download e-tax, you'll have to visit this link to the Australian Tax Office's website. Do not download anything that says it is e-tax from any other website -- it's like picking up food off the ground and eating it; you just don't know where it's been and what viruses it's picked up. Just go to the one and only official source, or lodge online through myTax instead (no downloads of anything needed!).
Can't get through to the ATO website? That's not surprising, since it's struggling under the traffic of thousands of people trying to do their tax returns as quickly as possible. The ATO's website is understandably under a bit of strain today, what with it being the 1st of July, but you can still get through if you try for long enough. Or you could just wait for a couple of hours, or until tomorrow, before trying again.
Also worth remembering is that www.etax.com.au is a third-party, commercial tax operator and not an official Australian Government website. The one you're looking for? That's www.ato.gov.au. Don't pay for a third-party service unless that's actually what you want to do -- the government will never charge you to download e-tax and do your tax return yourself.