A barrister representing Craig Thomson has told a judge the former federal MP lied about using union money to pay for sex because he was "under attack for moral turpitude" at the time.

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.