Alison Christie Mains, 41, was on Wednesday sentenced to three years in prison but will be allowed to serve it through a good-behaviour bond that requires her to seek medical treatment and not consume drugs and alcohol.

The cognitively impaired woman pleaded guilty to six charges over her ruse that her severely disabled daughter was still alive despite the girl dying aged five months in 1998.

By the time the lies were exposed in 2013, she fraudulently claimed $39,400 in the childcare allowance, $83,700 for the single parenting payment and $85,900 for the family tax benefit.

"Despite her limitations, she ably facilitated the falsity of her daughter's death," NSW District Court Judge Nicole Noman said.

"She didn't merely misrepresent her daughter's death ... she created scenarios to ensure payments."

Judge Noman considered Mains' early pleas and recent, lengthy stints in rehabilitation facilities when imposing the bond.

Australian Associated Press