You might think that any business the Australian Taxation Office contracts out work to would be a model corporate citizen with no question marks over its tax affairs or corporate history.

Key points: The ATO has paid the global business outsourcing company Stellar $150 million since 2012 to runs its call centre

The ATO has paid the global business outsourcing company Stellar $150 million since 2012 to runs its call centre Stellar has been investigated for shifting funds from a European subsidiary to a tax haven before being bankrupted

Stellar has been investigated for shifting funds from a European subsidiary to a tax haven before being bankrupted Stellar's parent company in the US has a history of complex related party transactions and ties to tax havens

You might be wrong.

Stellar is a privately owned call centre and "business process outsourcing" business with ties to a Texan millionaire family with a controversial corporate history.

A one-time subsidiary, which operated Stellar call centres in Britain, has what a critic calls "a bankruptcy trail stretching to the British Virgin Islands".

Stellar has benefited from contracts worth more than $150 million from the ATO since 2012.

It was recently awarded a $77 million contract to handle Centrelink calls for the Department of Human Services.

At the company's call centre at Maroochydore on Queensland's Sunshine Coast, workers taking inquiries on behalf of the ATO toil away on not a lot more than the minimum wage.

Few know that Stellar's money trail extends across the globe.

Though headquartered in Irving, Texas, the Australian subsidiary's ultimate parent is registered in Nevada — a state with a reputation for tax secrecy.

UK bankruptcy

Stellar calls itself "the voice behind some of the world's most loved brands".

It boasts of its "expertise in the end-to-end customer journey" and takes pride in being named "outsourcer of the year" six times.

Despite this, its UK business did not fare well.

On May 22 this year, Stellar Europe LLC — the company behind the UK call centres — filed for bankruptcy in Nevada.

The filings say that Stellar Europe LLC was entirely owned and controlled by Tensor Limited, a company registered in the British Virgin Islands, a notorious tax haven.

On March 2, just under $US122,000 ($160,000) from Stellar Europe LLC, was transferred from Stellar Europe to Tensor Limited in the British Virgin Islands — the money variously described as a "service agreement fee" and a "fee for management serviced rendered".

Employees, trade creditors and the UK tax authority, Her Majesty's Revenue and Customs Service, were not so fortunate.

The UK tax office was owed $US82,666 ($115,00) in payroll taxes and $US139,944 ($194,000) in sales tax when Stellar Europe LLC went under.

Court documents filed in Nevada say that Stellar Europe LLC was entirely owned and controlled by Tensor Limited. ( Supplied/ABC News: Alistair Kroie )

The bankruptcy filings say Stellar LLC, the ultimate parent company of the Australian business, transferred ownership of Stellar Europe less than six months before the bankruptcy.

According to Stellar, this was "an arm's length sales transaction with a third party". It did not identify the buyer, claiming "the terms were commercial in confidence".

In a statement, it told the ABC that at the time of sale, Stellar Europe "was a going concern and the transaction was conducted in good faith".

"The acquirer had permission to continue using the Stellar brand name for a set period of time after the transaction close date," the statement read.

"The conduct of the acquirer has no bearing or connection to Stellar's brand or reputation."

Bankruptcy shines a light into corporate structures

Strangely, Stellar Europe continues to be listed as a portfolio company on the website of a private equity firm — Hawkestone Asia Pacific — which is the local offshoot of a firm associated with the Texas family behind Stellar Global.

"The bankruptcy filings give a rare insight into the company structures," said Jason Ward, spokesman for the Tax Justice Network and principal researcher at the Centre for Corporate Tax Accountability and Research.

Mr Ward has been digging into Stellar Global for most of this year, with financial support from Public Service International, a global trade union federation representing organisations with 20 million members.

Stellar operates call centres around the world, including in the Philippines. ( Supplied: Stellar )

The outsourced call centre business is one of many private equity investments associated with the Jensen family, which has a long business history in Texas and operations around the globe.

Ron Jensen, the patriarch who died in 2005, made a fortune establishing and growing a big US insurance company, UICI.

But UICI drew heat from shareholders, insurance policy holders, regulators and business journalists for related party deals that were seen to benefit the Jensens.

In a lawsuit seeking access to company records, a shareholder, Amalgamated Bank, complained of transactions totalling tens of millions of dollars "between UICI and Ronald Jenson [sic] … his children, and various entities controlled by Jensen and his children" which had been "lucrative for Jensen and his confederates".

An article on "crony capitalism" in the business journal Forbes reported on multiple lawsuits that alleged UICI was concealing "an incestuous relationship" with a non-profit organisation — which purported to be independent but was allegedly run by Mr Jensen's children and former business partner to sell UICI insurance.

Related party transactions

A multi-state investigation by insurance regulators in 2005 noted: "The founder of UICI and primary stockholder, Ronald Jensen, was the target of lawsuits and allegations that he had established channels of multiple streams of income for himself, family members, other stockholders, agents and executives of the Company, at the expense of policyholders".

Insurance regulators raised concerns about a lack of transparency in the relationship between UICI and "member organisations" associated with the company.

The insurance business strenuously denied it was using non-profit organisations and other vehicles in any improper way. It reportedly settled a number lawsuits out of court.

The ABC tried to contact the managing director of the company that handles the Jensen family office by phone and email, but received no response.

"It's a pretty sketchy history of related party transactions," Mr Ward said.

"When you've got a history like this, there is cause for concern."

Stellar's Australian operations

Stellar told the ABC in a statement that it was "important to note that Stellar group operations are managed out of Australia".

"Stellar," it maintained, "has a proven track record of strong corporate governance and good corporate citizenship, which is evidenced by its Board and Committee Structures, comprehensive policy and procedure framework and strict adherence to statutory and reporting deadlines and payments".

But after forensically examining the filings of Stellar group and its back story, Mr Ward has his doubts.

"Are Stellar's related party transactions being used to reduce Australian tax payments and further enrich family members?" he asks.

"Are Australian governments aware of the background of this company?

"Is this the type of company that should be handling sensitive and private information about Australians on behalf of the ATO and the Department of Human Services?"

A report Mr Ward authored on the issues is soon to be released; Stellar rejects the criticisms.

The ABC asked the ATO whether it was aware of the history of allegations about related party transactions of past companies associated with some of Stellar's investors and directors, and whether it knew of the Nevada bankruptcy filings. It would not say.

It said: "The ATO follows the Commonwealth Procurement Rules, requires suppliers to provide warranties that they are compliant with Australian tax laws and engages probity advisers or conduct checks as appropriate."