The former principal of Moonee Ponds West Primary School who signed off on more than $90,000 in invoices to companies affiliated with sacked Education Department finance chief Nino Napoli said Mr Napoli was "charismatic" and had rendered Victoria's school system the "best funding system in Australia".

Anthony Hilton, who authorised $90,630 in payments to companies associated with Mr Napoli between 2007 and 2014, said he had no reason to question the invoices Mr Napoli asked that he pay, as Mr Napoli was the "go to" man for all things financial.

"There would be people lining up at his door ... lining up to talk to him about processes and programs," he said.

"He made some major changes to the Victorian funding system ... [it's] probably the best funding system in Australia".

Mr Hilton authorised a payment of $6820 at the request of the department's former acting secretary, Jeff Rosewarne, in 2009, believing it was for a "road show".

This payment contributed to Mr Rosewarne's Christmas Party at Oakleigh Bowling Club.

Asked if he would have reconsidered paying the amount if he had known what it was for, Mr Hilton said he "probably would have paid it anyway".

Mr Hilton also signed off on $2000 invoices that paid for food at an event marking Mr Rosewarne's return to the department after his secondment to the Victorian Bushfire Reconstruction and Recovery Authority.

A further $3000 was paid by the school for table seating at a fundraiser for The Alannah and Madeline Foundation, while other payments of several thousands of dollars were for computers that were delivered to Mr Napoli.

It was also heard that a former principal of a non-banker school, Brighton Primary School, Gordon Pratt authorised a $4824 invoice payment in 2008 at Mr Rosewarne's request, but was unsure what the money was for.

IBAC heard this amount also contributed to Mr Rosewarne's Christmas party, thrown in 2009.

"I did think it was unusual ... even if I had a query about it who would I go to?" he said. "He [Mr Rosewarne] is a very powerful man, he is not a man you would normally say no to."

Mr Pratt also paid over $5099 from school funds to Mr Rosewarne in 2009 for two coffee machines – a cost that was not reimbursed.

The machines were requested by Mr Rosewarne's office, after he had tried the coffee at Brighton Primary School during a school visit.

This purchase chewed up more than half the limit on the school's credit card.

Earlier in the day, IBAC heard Mr Napoli's two sons were paid for "volunteer" work via a company owned by their aunt, and for work they did not do at Maribyrnong College in 2008 and 2009.

Assistant principal of the college Robert Carroll said he had "no knowledge" of the payments and he would not co-operate with Mr Napoli's request that he claim their wages were legitimate.

The commission is investigating claims that 17 companies linked to Mr Napoli and nine of his relatives received more than $2.5 million from Victorian schools between 2007 and 2014 through the banker school system.

The hearing continues.

An earlier version of this story incorrectly named Anthony Hilton as principal of Moonee Ponds Primary School. He is principal of Moonee Ponds West Primary.