The 52-year-old man pleaded guilty at Bendigo Magistrates Court on Thursday to three counts of obtaining financial advantage by deception.

Federal prosecutor Raphael de Vietri told the court between February 2010 and October 2013, the man, who was receiving a disability pension, under-declared his earnings to the Department of Human Services.

Mr de Vietri said the man earned $100,238 during this period while working as a security guard at a Bendigo security firm, but only declared earnings of $12,458, scooping $27,172 in extra social security payments.

The court heard when the fraud was detected during a data-matching exercise between the Australian Taxation Office and Centrelink, the man began to repay the amount.

The man's defence lawyer told the court his client was a former policeman in Victoria and New South Wales who had left the force after a series of traumatic events.

He said the man suffered pervasive, life-long post traumatic stress disorder and chronic depression, had a gambling problem and had become destitute after a bank foreclosed on his home.

He said his client didn't realise he was committing an offence at the time, and was "profoundly remorseful".

He conceded the offending was serious, but urged the court to impose a non-conviction bond which would allow the man to seek further employment.

Magistrate David Faram said it was staggering to hear a former policeman did not realise his actions were against the law, particularly when the issue of social welfare fraud was so often in the public eye.

But he said he accepted the man's traumatic experiences had led to the circumstances of his offending, and acknowledged his substantial contribution to the Victorian and New South Wales communities.

"You failed absolutely to abide by your lawful obligation. I do not condone the offending in any way whatsoever," Mr Faram said.

Mr Faram imposed a two-year Commonwealth bond and ordered the man repay the outstanding $25,456.

He also ordered the man continue mental health counselling and treatment.

The maximum penalty for one count of obtaining financial advantage by deception is 12 months' jail, a $6600 fine, or both.