But a few hundred dollars here and there added up over three years and Mauger was shocked not only to learn she had stolen more than $850,000 - but that she had nothing to show for it.

Except a more than three-year prison sentence, of which she must serve almost two years before becoming eligible for parole.

She was 52 and a woman with an unblemished record when she made the first illegal transfer from the company accounts she had access to as the office manager and bookkeeper for the Sandringham real estate firm in December 2016.

Mauger had held the position since 2011 and considered the company directors - one of whom has since had to delay his retirement for several years - as close friends.

She followed that first theft of $200 with more than 200 transactions over the next few years, moving sums ranging from $20 to $10,500 between two office accounts and two accounts in her own name.

Mauger used subterfuge to cover up her wrongdoing, County Court Judge Rosemary Carlin said on Friday.

Almost every illicit transfer was disguised within a groups of payments, always for larger amounts, to legitimate creditors.

She recorded false names of creditors and listed the payments as printing or advertising. She hid her account names, replacing the field with "DM", "MetroMedia" or sometimes just "account".

All up Mauger took $858,648.03.

Her offending was uncovered when the company's accountant noticed discrepancies with the books. He questioned Mauger, who tried to fudge it, Judge Carlin said.

Mauger resigned before he could report his concerns but was later arrested.

"I can't deny it," she told police, but expressed shock at the sum and said she had nothing to show for it.

Analysis of her bank statements showed more than $250,000 was withdrawn as cash, consistent with her gambling and use of poker machines. She also spent $7000 on lotteries, $12,000 on travel and a whopping $66,000 in the Apple iTunes store.

Mauger told a psychiatrist she had felt under financial pressure because her husband was unemployed, and that she had started gambling to win back what she stole, finding herself in a downward spiral.

Family, friends and subsequent employers described Mauger as reliable, honest and loyal and said she had told them of her offending.

"It's hard to reconcile the person described in those references with the person who acted so selfishly and dishonestly over those three years," Judge Carlin said.

She was sentenced to three years and three months behind bars. She'll be eligible for parole after serving 22 months.

Australian Associated Press