The new Commissioner of Inland Revenue Naomi Ferguson has acknowledged the major task ahead when it comes to replacing the computer system built for Inland Revenue 20 years ago.

Replacing Bob Russell in the role, Ferguson now heads a company focussed on shifting the ways people interact through the digital revolution.

Ferguson is tasked with replacing a computer system built for Inland Revenue 20 years ago, with an estimated cost reaching $1.5bn over the next decade.

"The work we have under way is about saying, okay, given what modern technology allows you to do, given what customers expect and want to do, how do we put all that together to create a very different type of tax department," says Ferguson to the New Zealand Herald.

"When it was built, Microsoft was a start-up firm and there was no internet.

"It does not, therefore, cope well with demands for online access."

Yet Ferguson told the newspaper she remains impressed by the latest technology used by the Inland Revenue, noting:

"You register your voice, which is as unique as your fingerprint.

"We have 400,000 people using it. It means that when they phone up to do something they can go straight through to a system without having to go through the 'what's your mother's maiden name?' business."

As the organisation introduces modern day technology in the form of a new mobile phone app launched in April this year, Ferguson says the number of users registering online with Inland Revenue has grown dramatically.

Yet Ferguson says the core function of the Inland Revenue remains the gathering of tax revenue, meaning a balance needs to be struck between making it easy for compliant users and tough for those who choose not to.

"If people want to get it right, but there's something going on with their life that means it's going to be hard ... we'll try to find ways to make is easier," she says.

"We've had over 50 successful prosecutions in the past year; last week we saw the longest sentences (about eight years) ever handed down for tax fraud."

To read Naomi Ferguson's full interview with the New Zealand Herald click here