A Dublin man who fraudulently claimed over €50,000 in illness payments while he was working is complaining that his €75 weekly repayments are too high.
The man committed the fraud over a five-year period but is now on a disability pension of around €200 per week.
He is complaining that his €75 repayments are too high – even though it will take 13 years to repay the money defrauded from the Department of Social Protection.
Her intervention has raised questions about Sinn Fein's attitude to social welfare fraud.
Ms McDonald said she did not want to comment on the man's case because of his right to confidentiality, but denied that her party was "soft" on social welfare fraud.
"In no way am I condoning any individual who would try to be sly with the system. The department should look for the money back but they have to make sure that the people paying back aren't left in a situation where they are destitute," she said.
On the basis of disability pension payments of between €193-€230 per week, the man has a minimum of €118 and a maximum of €155 to live on per week.
Social Protection Minister Joan Burton has promised that the man's "overpayment recovery plan" will be reviewed as soon as he sends in a letter to her department containing full details of his ability to repay.
The department has confirmed that the man, who lives in Dublin's north inner city, had claimed a total of €51,305 while he was working between January 2005 and March 2010.
He was getting an invalidity pension, which is given to those who are "permanently incapable" of work because of illness or disability.
It was possible until recently for people to work part-time while getting the payment, but permission had to be obtained from the department.
The department confirmed that the man had not been given any such permission while he was working.
But it refused to say what type of work he was doing, and whether it had brought a prosecution against him. The department said it did not comment on individual cases.
Officials said 675 prosecutions for social welfare fraud were in the courts system at various stages of the process.
Last year, the department carried out a review of 10,000 people on invalidity pensions, which resulted in 942 having their benefits cut off.
The number of people who lost this benefit the previous year was just 19.
New figures show that 28,000 people provided tip-offs about suspected social welfare fraud last year, up from 16,920 in 2011.