Disgraced former Victorian Liberal Party director Damien Mantach has been sentenced to five years' jail for stealing more than $1.5 million from state party coffers.

He pleaded guilty to 15 charges of obtaining financial advantage by deception over an elaborate scheme to steal money from the party executive using fake invoices from June 2010 until just after the 2014 election.

The judge said while Mantach had made a full confession and suffered a humiliating fall from grace after being caught, she had no choice but to send him to jail.

Mantach was supported in court by his parents and a family friend, and as the judge handed down the jail term a voice could be heard to exclaim, "bloody hell".

Court documents revealed Mantach amassed a small fortune through kickbacks from inflated printing and logistics invoices from one of the party's official suppliers, Melbourne Mailing.

He generated 53 false invoices over four years, including to get funds through two of his own companies, Campaign Mail Logistics and Parkstreet Online Solutions, for research projects, logistical support and delivery of material that was never supplied.

But he told police he always expected to get caught and there was no control or oversight within the party over invoices.

Mantach stole money in bid to save marriage

The court heard his elaborate scheme was put into play to pay off debts and partly to save his failing marriage.

More than $506,600 was used to purchase shares, $81,859 was spent on a luxury car, $45,000 was used for home loan repayments and $535,085 was invested in a cafe for his wife at Ocean Grove, it heard.

The court heard his wife had no idea of the scam and his troubled marriage ended as soon as he was caught.

Mantach told his psychologist his significant debts had made him feel "inadequate" and pressured. However he continued to steal after they were paid off.

During his trial, Mantach said:

"For me it was actually never about greed, it was never about ... going off and getting a whole heap of lovely materialistic things. I took money, it basically relieved pressure in my personal life."

Only a third of the money stolen has been recovered.

'Levy' added to invoice as part of scam

Mantach was first interviewed during a Liberal Party audit in August last year where he admitted everything.

As part of the swindle, he had instructed Melbourne Mailing to add a levy to "random" invoices sent to the party, as well as MP offices.

One of the first scams involved an invoice in June 2010 for $16,800 in which 48 electorates were each charged $350 for printing and mailing expenses.

Yet Mantach said he did not take all of the money for himself.

"Some of the invoicing would actually allow us [the party] to pay for ... other work or activities, so it was all quite legitimate but it was all mixed in," he told auditors.

Mantach told auditors it was common practice for parties to pay inflated invoices from printers and other suppliers in order to divert funds to other areas.

The Victorian Liberal Party has since unveiled sweeping reforms designed to protect the party's finances. The party told the court Mantach's actions were a betrayal.

"It was a breach of trust for the hardworking volunteers and supporters of the Liberal Party and I'm pleased that this matter has now been concluded," Victorian Liberal MP Edward O'Donohue said.

Mantach moved to Victoria in 2008 after serving as state director with the Tasmanian Liberal Party from 2005.

He has already served eight months in custody and will be eligible for parole in two years.

The protracted crimes Mantach pleaded guilty to could have seen him jailed for 20 years.