Sajad Sanouli arrived in Australia about decade ago on a temporary working visa.
Like many migrants, he was taken advantage of by multiple employers and claims he was underpaid by about $20,000.
"You have no English, no rights, and you pretty much have no other choice," he told ABC News.
"We really didn't know better. We were taken advantage (of)."
Mr Sanouli was paid cash in hand, so he felt he couldn't report being underpaid.
"We would be threatened: 'If you tell the government, if you report, you are the person who's going to be in trouble. You have no right to work here. It will affect your visa, it will affect your profile in this country'."
That's a common threat that stops migrants from speaking out, and according to the Grattan Institute, there's tens of thousands of migrants in Australia who get underpaid.
Its report released this week found that one in six migrant workers were paid below the national minimum wage, and that many don't report the underpayment because they fear they will be punished for breaching their visa rules and lose their pathway towards permanent residency.
And while underpayment is an issue that also impacts Australian workers – Grattan's report says that between 3-9 per cent of Australian workers are paid less than the minimum wage — migrant workers have it worse.
Agriculture and hospitality 'worst' industries for underpayment
Migrant workers are 40 per cent more likely to be underpaid than long-term Australian residents.
"Migrants are more vulnerable to exploitation because they've often been here for less time," Grattan Institute economist Brendan Coates said.
"Many don't have such strong English skills, but their visa conditions also reduce their bargaining power with employers.
"Migrants are also more likely to work in industries where underpayments are higher like agriculture and hospitality."
Josh Strutt, centre director and principal solicitor at Immigration Advice and Rights Centre, gets referrals on a weekly basis of migrants who are being exploited.
He said these migrants were scared to report dodgy employers because they fear it will risk their pathway to permanent residency.
"People need to have the freedom to speak out without fear of adverse consequences to their visa," he said.
"And in line with that, there needs to be a whole raft of protections then implemented through the migration system to ensure that people's visas are certain, safe and that they don't jeopardise their future in Australia."
When migrants don't get paid properly, that affects all workers
Fiona MacDonald is policy director, industrial and social with the Centre for Future Work, and said the issue had ripple effects across the economy.
"If migrants are being underpaid wages, other workers aren't able to demand higher wages or to bargain for higher wages, so their wages will be lower than they might otherwise have been," she said.
The federal government is expected to soon announce reforms to tackle migrant worker exploitation.
Immigration Minister Andrew Giles told ABC News the measures would make it easier for vulnerable migrants to speak out by protecting them if they were exploited.
Grattan's Brendan Coates was hopeful government action was on the way. Grattan's report calls for an overhaul of visa rules and tougher policing and penalties.
"First, we need to reform those visa rules that make temporary visa holders more vulnerable to exploitation," Mr Coates said.
"Second, we need to better enforce our workplace and migration laws to stamp out underpayment by bad faith employers.
"And third, we need to make it easier for migrants and Australian workers alike to get their back pay to seek repayment through the courts."
Sajad Sanouli would have benefited from better protections.
He hopes changes are on the way that will ensure other workers don't get ripped off.
"I just simply don't want others that are new in this country, to (face) the same situation as me … because honestly, it's awful."
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