Former federal parliamentary speaker Peter Slipper has been found guilty in the ACT Magistrates Court on three counts of dishonesty over the misuse of his parliamentary Cabcharge allowance.

A hearing began last week into charges that Slipper misused his Cabcharge allowance on three occasions, including to wineries, in 2010 before he was appointed speaker.

The total bill for the three trips was believed to be just more than $900.

On the first occasion in January 2010, Slipper visited up to six premises including the prestigious Poachers Pantry and Clonakilla wineries.

A hire car driver gave evidence that he drove Slipper and another man to several wineries and at the end, Slipper asked him if they could split the payment up into four amounts "because it would make processing easier".

The court also heard evidence from a second hire car driver, who drove Slipper to wineries on two other occasions.

Chief Magistrate Lorraine Walker on Monday found Slipper falsely recorded the travel he took on those three days and that he gave a disingenuous description of the trips.

As the matter was prosecuted summarily in the ACT Magistrates Court, the maximum penalty the court can impose is 12 months imprisonment or a fine of $6600, or both, for each offence.

He will be sentenced on September 22.

On Thursday, Slipper's lawyer asked the court to throw out the hearing and find there was no case to answer, but the Chief Magistrate dismissed the application.

Lawyer Kylie Weston-Scheuber had told the court the prosecution failed to prove that her client was not on parliamentary business because there was no legal definition of the term.

But prosecutor Lionel Robberds told the court the trips were clearly not parliamentary business and Slipper had filled in multiple travel vouchers in a bid to hide the fact.

In the end the Magistrate ruled that was not an issue she needed to deal with, as the main question was whether or not he had been dishonest.

Last week, Slipper admitted using taxi vouchers to visit wineries around Canberra but denied doing so dishonestly.

Multiple challenges to get case thrown out

Thursday's application was the third attempt to get the charges against Slipper thrown out of court.

A previous challenge by Slipper, based on mental health concerns, was thrown out in June.

Slipper wanted the court to set aside the charges because he was suffering a major depressive disorder, which was made worse by the case.

The court previously heard he had been hospitalised several times and had been having suicidal thoughts.

Earlier this year, Slipper also lost a bid to have the case thrown out on the basis he could not defend himself without breaching parliamentary privilege.

Slipper lost the Queensland seat of Fisher in the 2013 election when he ran as an independent, after splitting with Coalition colleagues when he accepted Labor's offer to be Speaker in the House of Representatives.

He had held the seat on and off since 1984, first for the National Party and later for the LNP.

Slipper resigned as speaker in October 2012 amid a sexual harassment claim brought by his former staffer James Ashby.

Mr Ashby recently abandoned his claim against Slipper after a two-year court battle.