Thomson, 50, was in March jailed for three months, with nine months suspended for two years, after a magistrate found he used more than $24,500 of Health Services Union funds for personal benefit while he was the union's national secretary from 2002 to 2007.

But the former Labor member for the NSW seat of Dobell has not served any of that jail term because his legal team launched an immediate appeal against the conviction imposed bymagistrate Charlie Rozencwajg.

The appeal before County Court judge Carolyn Douglas finished on Tuesday. She is due to announce her finding on December 15.

Barrister Greg James, QC, representing Thomson, told Judge Douglas on Tuesday that his client lied to Channel Nine's Laurie Oakes in a May 2012 interview at the height of the scandal.

That was the interview in which Thomson claimed he had been set up by union rival. Mr James said Thomson lied to Oakes to divert attention away from him because "he was under attack for moral turpitude".

"To rebut that, he lies," he said.

Mr James told the court Thomson was not guilty of theft or obtaining a financial advantage by deception because any money he withdrew from ATMs with union-issued credit cards belonged to the bank and not the HSU.

He said the charges could not be proven the way they were worded.

"It might be that some different financial advantage or disadvantage might be alleged," Mr James said.

"But as these charges, for both theft and [obtaining] financial advantage, are brought, it is our submission that the case against him is not made out on the evidence ... and on the way the charges have been preferred."

Mr James said there was duplicity in the charges laid against Thomson, because the Office of Public Prosecutions had charged him with theft for withdrawing money from an ATM and then a deception charge for using the money.

Thomson was convicted in March for using HSU-issued credit cards and a Flight Centre account to pay for sexual services and to withdraw cash from ATMs, and to buy cigarettes, firewood and travel expenses for his then wife, Christa, while he was the union's national secretary.

Lesley Taylor, SC, representing the OPP, said on Monday Thomson had never been authorised to use HSU funds for himself.

Judge Douglas said on Monday the appeal was in effect a new hearing and that she therefore had the power to impose a bigger jail term if she ruled against Thomson.

Ms Taylor told the court on Tuesday the matter could return to Melbourne Magistrates Court if the judge ruled against the OPP.

Thomson lost the seat of Dobell in last year's federal election when he stood as an independent.

Thomson is on bail while he awaits Judge Douglas' ruling.