Do Australians think the tax office is fair?

For the ATO, it's the million-dollar question. Or make that, $973,530 (excluding GST).

That's how much the ATO paid international market research firm Kantar Millward Brown over four years to quiz Australian individuals and businesses about their interactions with the taxman.

The latest survey results, obtained by the ABC under freedom of information laws, revealed 44 per cent of taxpayers surveyed did not agree that the agency was fair or professional in handling tax disputes.

Less than half said they were kept well-informed about the process of their dispute, while 45 per cent did not agree the time taken to resolve their dispute was reasonable.

The ATO declined a request for an interview, but in a statement said it commissioned the rolling survey to help develop "fairness metrics across the organisation".

"Regular fairness data and insights allow the ATO to increase its responsiveness to changes in community perceptions," the ATO said in statement.

"These insights are used internally to drive a range of activities that focus on delivering an experience to both taxpayers and tax agents they perceive to be fair. Some examples include fairness training for all team leaders in client-facing areas."

The ATO said those strategies had led to an increase in the proportion of taxpayers who believed they had been treated fairly, from 50 per cent when the survey began in 2014, to 56 per cent last year.

The lukewarm responses come in the wake of allegations of bullying and heavy-handed treatment of small businesses by the ATO, aired in a joint ABC-Fairfax investigation in April.

ATO whistleblowers told Four Corners the agency was unfairly targeting vulnerable small businesses in order to reach internal revenue targets.

Small business owners accused the tax office of heavy-handed treatment during disputes, including cancelling tax-payers' Australian Business Numbers without warning.

Small business advocate Ken Phillips, who spoke out as part of the Four Corners investigation, said the ATO should be ashamed of the results of its survey.

Ken Phillips said the survey results should be considered a "disaster." ( ABC News: Mathew Marsic )

"The ATO presents the report as a positive because there has been an increase in taxpayer perceptions of fairness since 2014," Mr Phillips said.

"If the ATO were a business, the report would be considered a disaster.

"The survey results add justification to our calls for major reform of the ATO."

The Four Corner's report triggered an investigation by the Inspector-General of Taxation, Ali Noroozi.

His investigation's final report, which has also been released under freedom of information laws, called on the ATO to improve its handling of disputes with small businesses.

"The ATO must appreciate the power that it holds over the vast majority of citizens with whom it interacts and reconsider its strategy when concerns of the nature identified in the Four Corners program are raised," Mr Noroozi wrote.

"While it is undeniable that there have been many commendable ATO initiatives over the years, it needs to ensure that when approached with concerns, it considers them fully and genuinely and be seen to be doing so rather than be perceived to be diminishing the concerns and those who raise them."

The Inspector-General of Taxation's report also recommended funding or other assistance should be provided to taxpayers who could not afford legal representation in their disputes with the ATO.