The changes, which include penalties of up to $1.5 million for individuals and $5.5 million for individuals, were introduced into the NSW parliament on Tuesday after a scandal over confidential federal tax briefings being leaked by a former PwC partner.
NSW Finance Minister Courtney Houssos said the government was putting people on notice if they actively and deliberately sought to mislead for their personal gain.
"This isn't just about deterring people from doing the wrong thing but also holding people to account for their deception," she said.
The state government said it routinely consulted with external representative industry bodies on tax policy and legislation on a confidential basis.
The penalty regime, which will require crossbench support to pass, also applies to those who conceal the breach of confidential government taxation information.
It allows the Chief Commissioner of State Revenue to report offenders to professional bodies and publish relevant details.
"These measures ensure integrity remains at the heart of the NSW government's tax system," Ms Houssos said.
"The new multimillion-dollar penalties send the strongest signal yet that divulging confidential government information won't be tolerated."
An upper-house inquiry last week was told drastic action was needed to curb problems with consulting firms that walk both sides of the street by working for the government and private clients in the same area.
Academics called for "big four" firms - PwC, KPMG, EY and Deloitte - to be forced to split their audit and consulting arms
"That will be the only way we can get around the conflicts of interest," Macquarie University professor James Guthrie told the inquiry.
The amendments to the system of fines in NSW will also create an offence for a person who offers or agrees to be falsely nominated, including for driving and traffic offences.
It's already an offence to nominate another individual but those taking the demerit points on false pretences will also face a fine of up to $5,500.
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