Alison Christie Mains, 41, is awaiting sentence in the District Court after pleading guilty to three counts each of obtaining financial advantage by deception and defrauding the Commonwealth via the Department of Social Security.

"The offending began as a result of Ms Mains' daughter dying in horrific, tragic circumstances, aged five months," her barrister Marty Bernhaut said on Wednesday.

The disabled baby girl died in mid-1998 and the debt came to the fore in 2013 - a period of 14-and-a-half years, he said.

The agreed facts state Mains claimed $209,114 in payments she wasn't entitled to, failed to notify Centrelink of the death and made false oral representations over the years her baby was still alive.

This constituted overpayments of Child Carer Allowance ($39,403.80), Parenting Payment Single ($83,741.46) and Family Tax Benefit ($85,969.32).

She also called Centrelink within two months of her child's death seeking advance payments doing so more than a dozen times and approximately every six months.

At times Mains told the government service her daughter was in "palliative care that day" or that she had used up her previous payments on medical expenses and costs associated with her child's neurological dysfunction.

These comments were all made after the baby's death in August 1998.

Mr Bernhaut said Mains "absolutely" accepts she was not entitled to the money for her deceased child.

But he also submitted she is illiterate, has never worked, has a background of "significant deprivation" and would have been entitled to $69,696.20 in Newstart allowance during the offending period.

He said a Centrelink investigator also established she could have received more than $189,000 in Disability Support Pension entitlements.

"The DSP she may as well have been eligible for ... was some $2500 more than the single parenting payment," Mr Bernhaut said.

He said his client has previously told medical practitioners the baby's death was "a particularly difficult, stressful event" and has since engaged in behaviour including dressing up a doll and pretending it was her daughter.

"She reports being emotionally distraught and in poor physical health at the time," the barrister said.

"It's patently apparent she deteriorated significantly in the period following her child's death."

Prosecutor Frank Farah said the defence case "in the best light" is that Mains may have been entitled to "something" from Centrelink.

"It was so speculative that you certainly can't give it a mathematical figure but you can take it into account subjectively," he told the judge.

Mains' deceptive conduct was conscious and over an extended period of time, he said.

"She intentionally deceived Centrelink so she could get more money."

The court heard Mains has spent periods in residential rehabilitation for alcohol dependence and may so again.

One count of robbery and four counts of larceny will be taken into account upon sentence.

The facts state Mains stole eight bottles of alcohol in 2017 including Jim Beam Bourbon and Smirnoff Vodka.

Mains will be sentenced on September 18 by Judge Nicole Noman SC.

Australian Associated Press