Parts of the Victorian roads authority will be partnered with the private sector, the government has announced, in a move a union has called a "part-privatisation" that is a "betrayal" of workers and motorists.

A scoping study found a "joint venture partnership" would be the best way to upgrade the authority's IT system to "develop modern registration and licensing services", the government said.

The government will maintain ownership and control of VicRoads.

In April, people will be able to take their learner driver test online for the first time, and the government has said similar initiatives will be rolled out in the future.

Treasurer Tim Pallas said every worker would keep their job, and could either stay employed by the government or move to the private sector.

"This is not a privatisation —it's effectively a partnership that hopefully will work for the Victorian people, that will hopefully get us the IT systems that they need," he said.

"It's about making sure that we retain that level of oversight and control that the community expects the state to be able to provide."

He said in the short-term, he expected about 100 jobs would be created.

But the Australian Services Union (ASU) slammed the overhaul, calling it "part-privatisation and a betrayal of workers and Victorian motorists".

"We fear this part-privatisation will see staff slashed, services fall, prices increase and be a genuine risk to the privacy of licence holders in Victoria," union secretary Lisa Damanin said.

"No other state government in Australia has part-privatised a road traffic authority. Victorians should not be the guinea pigs testing the impact of private sector partnerships on the delivery of such an essential service."

She accused the government of "following in the steps of Jeff Kennett", the former Liberal premier who oversaw the privatisation of a number of state assets.

The ASU said after traffic and road management responsibilities were moved to the Department of Transport last year, the remaining areas — licensing, registration and custom plates — would all fall under the new venture.

Mr Pallas said the private sector organisation would be found through a public tender process and would share a part of the profits over a 30-40 year period from licensing and registration.

He said the state would retain the majority of that money, but the size of the split with the private sector partner has yet to be determined.

Last year, licensing and registration were worth about $1.8 billion.

He said the government would never sell off VicRoads, adding pricing, customer data, access to the road system and road safety management would remain the role of the state.

The Victorian Greens' transport spokesman Sam Hibbins called the venture "yet another privatisation by the Victorian Labor government that will put the interests of private profit over the public good".

Opposition concerns about data security

The state opposition said the government could not be trusted when it came to keeping Victoria's data secure.

Opposition spokesman Brad Battin said the government had "effectively ruined ICT (information and communication technologies) projects right across this state continuously, they've admitted today that they can't do this one, so their answer is to privatise it".

"We simply can't trust this government when it comes to our data … Victorians must be concerned, I'm concerned if my data is going to be handed off without any guarantees that it's going to be protected by a government that has seen increases in data breaches continuously since they've come into government," Mr Battin said.

"We're not just talking about a driver's licence or a registration plate, this is the 100 points access to get you a home loan, it's the 100 points access to sign off on anything to identify you," he said.