Unpaid internships are increasingly becoming the default way of beginning a professional career in Australia.

According to the largest survey so far, 60 per cent of people aged under 30 have done at least one, but when it comes to the status of interns, the law is unclear.

Sorry, this audio has expired Listen to the whole story

One of the distinctions between an employee and an intern, according to the Fair Work Ombudsman, is that if the work "would otherwise be done by an employee, or it's work that the business or organisation has to do, it's more likely the person is an employee".

Up to half a million interns may have been in unlawful arrangements over the past five years, says Andrew Stewart, a professor of labour law at the University of Adelaide and co-author of the 2016 survey.

"We seem to be getting away from that idea about organisations investing in their workers and being prepared to put the time into paying them while they're on the job," he says.

"They say, 'Well, if they're not ready immediately to work for us then we'll just make them an unpaid intern.'"

"I think that's where organisations are taking a significant legal risk."

Most interns reported high satisfaction with their experiences, but there's no conclusive evidence that internships lead to employment outcomes. Many interns end up with jobs related to their placing, but they might have done so anyway.

We asked four interns and former interns about their experiences.

Carolina Flora Diaz, 31, graphic designer

Carolina made a complaint to the Fair Work Ombudsman after she she was refused a wage. ( ABC RN: Patrick Carey )

"They said there was a chance to work permanently with them, but this is what most employers say!"

Late last year Carolina Flora Diaz worked for two months for a small graphic design company, creating business cards, flyers, website design and other material. Carolina is from Argentina, and wanted Australian work experience.

The office was the company owner's apartment. She and three paid colleagues worked in the lounge room.

"When I went to the job interview I showed them my portfolio," she said.

They told me 'we can give you some work to do' but they didn't specify that the work would be for clients — I imagined it would be exercises or training."

After two months, she asked for pay if she was to continue, and the company owner refused — saying she was too slow and lacking in a key software skill.

Carolina left the internship and made a complaint to the Fair Work Ombudsman, which is still investigating.

Her advice for prospective interns: study the Fair Work Ombudsman guidelines, and "clarify the terms of the internship before starting it".

The University of Adelaide's Professor Stewart says internships are much safer, legally speaking, when they're an accredited part of a university or training course.

Cedric Giordano, 24, engineering student

Cedric is working as an intern for six months, half of which has been paid and the other unpaid. ( ABC RN: Patrick Carey )

"This internship has shown me a lot about engineering and a lot of what happens in the back scenes: communication with clients, dealing with fee proposals, a lot of documentation and tendering."

Cedric is a third-year student at the University of Technology Sydney, and as part of his course he is required to do a six-month internship. The first three months were unpaid, the second three paid.

It literally changed his life — the work convinced him to change his course.

"In my internship I'm involved with structural, hydraulic and civil engineers. I was doing civil engineering at university but because of my internship I've found a passion more in structural engineering."

There is currently an oversupply of engineering students, which means there's fierce competition for internships. Cedric says he had no contacts when he began the hunt for engineering companies via Google.

"I would have phoned probably between five and 15 companies a week. Then I took it up to myself to go around the city and physically go to these workplaces and ask around so I could see some faces and they could see me and see how I am."

Eventually, he found success — a firm in North Sydney took him on.

On the paid versus unpaid question, Cedric sees merit in both.

"I think it should be unpaid at the start, because you're there for the experience and you're there to learn and you're taking up a lot of time of the other engineers."

"When you get to a certain stage like I am, after three months, you know a lot."

Now Cedric is working a 45-hour week, and says he's glad to be getting paid, albeit at a relatively low rate.

"It means I don't have to dip into my savings to get lunch."

Sarah Ashman-Baird, 24, executive director of Interns Australia

Sarah is concerned that unpaid internships create culturally homogenous industries. ( ABC RN: Alex McClintock )

"Unpaid internships lock out certain people. If you can't afford to work for free, then unfortunately you just can't access that opportunity."

Sarah Ashman-Baird has a full-time job in marketing, but gives her time to Interns Australia, a voluntary advocacy and advice group.

She did two internships while at university — both arranged as part of her marketing course.

"I did one at a car manufacturing company in Melbourne, and that was over 12 months, a full-time internship, and it was paid," she says.

"It was really well structured, there were lots of learning and I felt that that contributed to the rest of my career."

Sarah's second internship, also in the manufacturing industry, was paid as well and she found it beneficial.

Interns Australia has a clear position on internships: they should be paid, well-structured, and interns should have similar opportunities to employees.

"Unpaid only works for those who can afford to work for free or who have their parents supporting them. And that creates more a homogeneous landscape of interns," Sarah says.

But doesn't lobbying for paid-only internships risk losing potential employers and opportunities?

Perhaps, Sarah says, but it's a risk worth taking for the greater good.

"We stand quite firmly on that, just because of the implications that it has longer-term. We don't want to create a systemic culture of unpaid internships in Australia.

"As more people are willing to do unpaid internships, then that unfortunately creates a kind of self-fulfilling prophecy."

Tanja Milosevic, 32, MBA graduate

Tanja sold all of her possessions to do a year-long, unpaid internship in Egypt. ( ABC RN: Jeremy Story Carter )

"It's really, really ludicrous to have someone work nine-to-five, five days a week, and not get paid."

After growing up in war-torn Bosnia and migrating to Australia at the age of 18, Tanja wanted to work in international development.

But she found that in this popular field of study, unpaid internships are expected.

After her first degree Tanja spent a year in Egypt working on refugee issues — unpaid. She sold all her possessions to do it.

Then she undertook an executive master's degree, studying international relations and business.

"The way the program is structured you have to choose between doing an internship or project-based work. And I chose an internship," she says.

"I knew I wanted to do an internship overseas, and preferably in my home country, and for an international non-governmental organisation.

"It took me about three or four months of just cold emailing and seeing what's available."

Tanja ended up working on a guidebook for diaspora refugees returning to Bosnia. There was a team of people, all doing the same work, Tanja says, and with similar qualifications. But she and a local man were not paid.

While not specifically referring to that experience, Tanja believes not paying interns is having a detrimental effect.

"People who are excluded from gaining entrance are all those people who can't actually afford to be unpaid. So are people from developing countries. Or people from lower socio-economic backgrounds."

That, she says, is a loss to the field of international development. Tanja now works in the corporate sector.

Disclaimer: ABC RN takes unpaid interns as part of a diversity-targeted program that contributes to interns' university course accreditation.