Accounts for the Sydney Institute lodged with the corporate regulator provide an intriguing glimpse inside Henderson's tax-exempt dining club.

Where to begin? Henderson, who strongly pursues allegation of conflicts of interest in the media, has closely guarded the identity of the institute's backers.

The accounts though drop two very big names – Qantas Airways and Telstra Corporation.

The pair are described as contributors rather than members. According to the accounts contributors provide the bulk of the institute's total revenue of about $1.3 million.

Some $902,000 came from contributors in 2013. But life is not so simple.

The institute's auditors politely queried whether the institute may have a GST problem after it emerged that Qantas was given free tickets to an annual dinner after giving thousands of dollars worth of flights.

PWC partner Paddy Carney wrote that contributions were "generally treated as GST-free as it is deemed that contributors do not receive any services in return".

Telstra, which "proudly supported" this year's annual dinner according to a promotional flier, also got free tickets to the event.

Henderson has been fairly quiet about the activities of the two corporate giants although in 2011 he wrote that "Qantas workers must face global facts of life" after chief executive Alan Joyce's decision to lock out workers. The piece appeared in Fairfax Media as well as on the Sydney Institute's website without any declaration.

A Qantas spokesman confirmed that the airline was a contributor to the Sydney Institute in 2011, saying they had sponsored the organisation for about eight years.

Gaining clarity from Mr Henderson on this and other points was not easy. He was reluctant to answer questions in detail saying he was "very busy".

"I am surprised that, once again, Fairfax Media's business reporters have focused on The Sydney Institute – which is a small company. Perhaps there is currently no real news in business of which you are aware," he said in an email.

But apparently he is doing a good job.

Mr Henderson – the institute's auditor, PWC, notes – was paid a $17,000 bonus last year for his performance in 2012.

He declined to say whether the payment was authorised by the board, chaired by Nick Johnson, or how it was calculated. Mr Johnson said he was "not able to add any further comment", to Henderson's response to Fairfax Media.

"As I said, [I have] nothing really to add to Gerard's factual confirmation of our sign-off process," Mr Johnson said.

It is not clear from the accounts what salary Henderson and his wife, Anne Henderson, who is the institute's deputy director, draw for their toil.

However the accounts show key management personnel were paid a total of $407,262 in 2013. According to the institute's website though Mr and Mrs Henderson are the only directors and they are supported by six assistants.

The auditors' report also revealed the leave entitlements for Mr Henderson, his wife, and executive assistant Lalita Mathias.

Ms Carney noted that the trio's annual leave "has been capped at 40 days each".

But again paperwork is incomplete "there is no formalised documentation in place for this entitlement", the auditor says.

Mr Henderson has long criticised journalist for taking "well-earned breaks" or as he likes to call them WEBs.

Journalists at Fairfax Media and News Limited are entitled to 33 days annual leave, which is recognition of working all public holidays except Christmas Day and Good Friday.

"Journalists invariably regard themselves as taking breaks which are well-earned. The rest of us mere mortals take holidays," Henderson wrote on his Media Watch Dog blog on July 4 this year.

He sought to clarify the auditors' statement about leave to Fairfax Media. "The annual leave entitlement is 20 days.  Unused annual leave can accrue up to a total of 40 days," Mr Henderson said.

The auditor suggested some room for improvement in the institute's paperwork, particularly in regards to membership subscriptions, which generated $74,643 in revenue last financial year.

"From our testing of membership income it was noted that for one of our samples a receipt had been shredded as the member had already renewed for 2014," Ms Carney said

"It is recommended that management maintain paperwork for a longer period to ensure there is appropriate supporting documentation for audit purposes".

Mr Henderson is unconcerned insisting the institute was given a clean bill of health.

"The institute met all its reporting and taxation requirements for the calendar year," he said.

The political forum has hosted speakers including Prime Minister Tony Abbott and his predecessors Kevin Rudd and Julia Gillard.

"The narrative between the institute's auditor and the institute's board related to the internal management of the institute and focused on process. That's all," Mr Henderson said.

The auditor also recommended that the institute "formalises a self-assessment of its tax exempt status on a yearly basis", which would require board approval.

An earlier version of this article incorrectly referred to Ms Paddy Carney as Mr Paddy Carney. We apologise for the error.

After declining to comment for the article, Nick Johnson submitted this letter to the editor following publication.