"I was pretty surprised. It's an amazing decline, and the numbers do tell a story by themselves," he said.
"The Government was warned in 2013 about systemic tax avoidance by multinational corporations. It seems they not only chose to do nothing, but rather than stepping up the police of tax avoidance they've let the auditing of large companies quietly collapse."
Shaw called for more resourcing of Inland Revenue, which he said had their funding for audits and investigations cut by around 10 per cent, from $190m to $170m, during the period in question.
Interview requests sent to Inland Revenue were answered in writing by a spokesperson.
"Tax compliance in 2016 is about much more than audits," the spokesperson said, adding that lnland Revenue had built a "close relationship" with corporates that helped create a "no surprises environment when it comes to tax".
Questions about why the number of audits increased markedly in the year to March - from 25 to 74 - were not addressed.
The spokesperson the introduction of basic compliance package policy in 2012 meant large companies were required to annually submit a wide range of financial information which led to fewer audits.
"Depending on the risk rating from the [basic compliance package], past history and other intelligence further review or in-depth auditors are carried out ... Which means we are continually reviewing these corporates' tax affairs and have reduced the need to undertake large audits."
The Inland Revenue spokesperson defended their approach and said: "It is believed that this comprehensive monitoring approach and success in the courts combating aggressive tax planning is leading to improved compliance and a reduced appetite for pushing boundaries among the corporate community."
Aaron Quintal, a tax partner with EY who give tax advice to a number a large companies, agreed the reduction in audits was due to increased scrutiny. "They're able to target things a lot better, and do more effective - and fewer - audits," he said.
"There is an interesting story there - people don't understand the amount of scrutiny the top end of town is under. There is this impression they're left to their own devices: And that's absolutely not the case."
The issue of corporate tax avoidance had steadily climbed up the public agenda over the past year.
In March, a major Herald investigation into profit margin differentials and profit-shifting found 20 highly profitable international companies made $20 billion in revenues from New Zealand customers but only paid a total of $1.8m locally in income taxes.
In May, Australian governments used its Budget to announce a crackdown on multinational tax rorting by imposing a "Google tax," the popular name for a diverted profits tax.
And last month the European Union stung iPhone maker Apple with a $20b tax bill after ruling it had used funnel international revenue through Ireland tax-free.
The move followed the United States' blocking of drug giant Pfizer's attempts to relocate to Ireland in a manoeuvre known as a corporate inversion.
