Those working as Uber drivers, letting rooms on Airbnb and offering services through Airtasker are in the sights of the Tax Office this year.
ATO Assistant Commissioner Kath Anderson says as the transactions are made electronically, they are easy to trace.
"We have more than 650 million pieces of data each year and we use that and other information that we have got to form a picture of someone," she says.
The Tax Office is using enhanced data matching protocols for the sharing and online economy, which is making it harder to taxpayers to hide income.
Under the Tax Office online selling data matching protocol, it collects data from eBay Australia and New Zealand of registrants who sell goods and services with a total value of $12,000 or more during the financial year.
Although, at this stage, the data is only being collected from eBay, the Tax Office says it may include other platforms.
If you do not make repeated sales and are not carrying on a business you do not have to declare income.
For example, If you sell household goods or possessions that you don't want anymore, you are unlikely to be carrying on a business.
Uber, Airtasker
Anderson says Uber drivers are treated no differently to taxi drivers as far as the tax law goes.
And income from renting out a room or a car space or offering services through Airtasker or similar platforms needs to be declared, Anderson says.
"Some people think that because they don't do it every weekend that they don't have to declare," she says.
Each and every tax return is now scrutinised by the Tax Office.
"We compare the person to their peers in a similar occupation and similar circumstances," she says.
If declared income and claims for deductions are out of kilter with peers the Tax Office takes a closer look, she says.
Another target this year is holiday homes.
Anderson says some people claim a whole year's worth of deductions when they are spending part of the year in the property themselves.
She says you cannot claim those expenses for the period of the year that you are residing in the property.
Work-related expenses continue to be another area of concern.
"The main areas are cars and travel and work-related clothing and self education," Anderson says.
With mobile phones you can only claim for the portion that is work-related.
Mobile phone and broadband expenses for work and personal use need to be clearly distinguished.
Anderson says that even for claims of less than $300, you still need to be able to prove that you have spent the money.
Claims for ordinary work clothes cannot be made. Claims can only be made for uniforms and protective clothing, she says.
How to lodge
Taxpayers can choose to lodge using the ATO's online lodgement tool myTax or they can lodge with a registered tax agent.
Tax returns need to be lodged by October 31. For those using a tax agent the lodgment date can be as late as May next year, so long as the taxpayer is not in dispute with the Tax Office.
If you're using a tax agent for the first time, or using a different tax agent, you need to contact them before October 31.
Anderson says 2.8 million people lodged their tax return in July last year, which is 22 per cent of all tax returns lodged for 2015-16.
"We know that some taxpayers like to get in early and lodge in the first month of tax time, but our analysis shows that if you lodge in July, you're far more likely to make a mistake by leaving out some of your income," she says.
"By mid-August we have pre-filled most of the data from employers, banks, government agencies and other third parties. Waiting until this information is available will help you avoid mistakes," she says.
"If you have been using the myDeductions tool, which is available in the ATO app, to save and store your deductions, you can upload that data as well without the need for physical receipts," she says.
For more information on how to lodge, visit ato.gov.au/lodgeonline and to find out about myDeductions, visit ato.gov.au/mydeductions.