A group of young conservative Liberal power brokers accused of soliciting illegal donations used some of the funds to pay for a bucks night, one of its members has told a corruption inquiry.

The Independent Commission Against Corruption (Icac) on Friday heard again from Robert Assaf, who this week was the first witness from the conservative right Liberal factional group the Reformers to give evidence.

The inquiry is investigating allegations that the Reformers solicited or accepted illegal donations to recruit or renew members to the party – a practice known as “branch stacking”. The group wanted more conservative policies on same-sex marriage, abortion and euthanasia.

The counsel assisting Peggy Dwyer SC asked Assaf about a decision to move alleged payments from prohibited donor Michael O’Hara from a bank account in the Reformers’ name to Beckington, a registered lobbying firm set up by the group and run by member Christian Ellis.

O’Hara earlier this week admitted to a fake arrangement in which he paid Beckington for “strategic wealth strategy investment advice”. He disputed whether the payments to the Reformers were to the NSW Liberals or should be considered political donations.

On Friday, Assaf said funnelling money through Beckington rather than the Reformers account was to create “the maximum benefit from a tax perspective”.

Dwyer replied: “That’s an explanation that you thought of overnight. Is that right?”

Asked if he was aware that it was illegal to minimise tax by creating fake invoices, Assaf said he knew that now, but not at the time. Asked if he thought the arrangement was “dishonest”, he said: “I would have thought it was tricky.”

Assaf admitted to temporarily using funds from the Reformers account to pay for a bucks night.

In a WhatsApp message to the group in August 2020, Reformer Jean-Claude Perrottet, the brother of former premier Dominic Perrottet, wrote: “Rob has the bucks cash coming back.”

Asked what this meant, Assaf said: “I think you recall I referred to us being immature and young, using the account as an advance on our personal expenditure.”

“This was one of those moments where we, I think, we had booked a venue for either my bucks or Christian [Ellis’s] bucks. It required an upfront payment.”

“I think it was cancelled, maybe because of Covid, one of them, so it was waiting for it to get reimbursed.”

The commission heard Assaf was employed in communications at Catholic Schools NSW, the governing body for 600 schools in the state, in 2019, alongside Reformers associate Dylan Whitelaw, who gave evidence earlier in the week.

The Catholic Schools NSW chief executive, Dallas McInerney, is alleged to have arranged and approved payments to the group to support branch stacking efforts through Beckington, where Whitelaw later came to be employed.

Under questioning from Dwyer before lunch, Assaf admitted that he knew that money being paid to Beckington was to fund work that Whitelaw was doing for the Reformers. “I knew that, yes,” Assaf told the hearing.

The inquiry on Friday returned to whether the federal opposition leader, Angus Taylor, had knowledge of and supported the Reformers.

Assaf said he recalled sending a screenshot of a message from McInerney in which he said he wanted to “shake down Angus for 10K”, and reading a message sent by Whitelaw in which he claimed McInerney had received “the commitment from Angus, the 15k injection plus a 3k monthly donation”, but denied any donation had taken place.

“I don’t think Angus worked out,” Assaf said. Taylor, who is not accused of wrongdoing, on Friday again denied making payments to the group.

The Icac presiding commissioner, Fabian Gleeson, intervened on multiple occasions during Assaf’s evidence. Before the lunch break, Gleeson told Assaf he had become “a bit argumentative in your response”.

“I believe they call that hangry commissioner,” Assaf said.

Gleeson said: “I’m not aware of what young people’s speak is these days, Mr Assaf. What I’d like you to do is to sit there, concentrate, and answer a further question which council assisting has, and then we’ll adjourn. Understand?”

On Monday, Icac is scheduled to hear from the NSW shadow attorney general and Liberal leader in the upper house, Damien Tudehope.

Many of the Reformers worked as staffers in Tudehope’s office, and Tudehope gave frequent talks at Reformers recruitment events. O’Hara is his former business partner.

Tudehope, who has stood aside from his shadow cabinet roles during the inquiry, is not accused of wrongdoing.

The inquiry will also hear from Jean-Claude Perrottet and Jeremy Greenwood, both named in Icac’s allegations. The watchdog heard on Thursday that Jean-Claude Perrottet allegedly paid for memberships as part of branch-stacking efforts, forbidden under Liberal party rules.

He has previously denied any wrongdoing, while Dominic Perrottet is not accused of wrongdoing.

Icac’s hearings continue.