The Australian Taxation Office has warned those intending to file tax returns via its online myTax platform to wait until August, when it can offer most of the third-party data it needs to pre-fill the forms.
From this year, the two-year-old myTax is the only way taxpayers can lodge their returns online, after the ATO puts its 17-year-old e-tax tool out to pasture in June.
Around 1.7 million people lodged their returns through myTax last year, according to the ATO, and it is anticipating 3 million this tax time.
MyTax prefills a person's return with information provided by their bank, employer, and government agencies, as well as from their previous year's return.
But despite tax time 2016 having begun more than two weeks ago, the ATO is urging myTax users to wait until August to file their returns. Over 500,000 people have already used myTax since July 1, the agency said.
ATO assistant commissioner Graham Whyte said the tax office won't have received all the third-party data it needs to pre-fill returns until next month.
Part of the impact likely lays with the delay to the arrival of tax statements for customers of health insurer Medibank following a data migration hiccup.
Ninety-six per cent of people who make mistakes when declaring their income lodge before pre-fill daata is available, the office said.
Waiting until August when the pre-fill data is available will mean "all [users] have to do is double-check the information we have pre-loaded for them, enter any deductions they have, and then hit submit," Whyte said in a statement.
Staggering returns will also help the ATO avoid the system load issues it experienced in the first two years of myTax's operation, which left many unable to lodge their forms.
This year also marks the first time the ATO will be able to check deductions in real-time through myTax.
“We want people to claim what they are entitled to – no more, no less. If your claims are substantially higher than others in similar occupations, earning similar amounts of income, a message will appear, asking you to check them," Whyte said.
Those signing up to use myTax are required to simultaneously create an account with the government's single sign-on portal for access to government services, myGov.