In a statement, the ATO said it was concerned at the number of individuals who are yet to lodge their return, with only 72 per cent of NSW taxpayers having completed the task.
The neighbouring ACT boasts the second lowest number, with only 75 per cent of tax returns lodged.
The ATO identified a number of reasons why taxpayers delay lodging their return, with the most common explanations including the individual being unaware they were required to lodge a return, expecting a large debt, being behind in lodging their returns from previous years or, simply, running out of time or not considering their return a priority.
“Of course, taxpayers are entitled to wait to the last minute to lodge. But we are concerned that taxpayers who do wait until the deadline rush their return and make errors while lodging,” said assistant commissioner Kath Anderson.
According to the ATO, the most frequent errors taxpayers make include leaving out income and claiming dedications that they are not entitled to.
Often this is because they have either re-lodged the same claim from last year or did not access all the information they needed to correctly calculate their claim.
Earlier this year, the ATO also announced that it will be using state-of-the-art data analytics to evaluate claimed deductions and work-related expenses.
Taxpayers are urged to remember that any deductions claimed must have come out of their own pocket and not been reimbursed, be directly related to their occupation and submitted with a record of purchase.
Failure to lodge can incur a fine of up to $1,050, with a $210 penalty added for every day up to 28 days after the return is due.