Fine Gael TD John Deasy accused Minister for Enterprise, Trade and Employment Micheál Martin of being "smug, smarmy and arrogant" in a reply to him about an anomaly in the community employment scheme.
"Nobody will starve over this, as we are talking about only €10," said Mr Deasy.
"However, at the very least, participants in community employment schemes deserve a ministerial response that does not insult their intelligence."
Mr Deasy said that a €20 increase in the Budget had raised the amount for a participant with an adult dependant in the scheme from €333.50 to €353.50.
"This sounds fine, except for the fact that, unwittingly, the €20 increase pushed this category of participants into the PRSI bracket and, in doing so, almost half of the increase was taken back in PRSI. Immediately and effectively, a €20 increase did not exist."
Mr Deasy added that community employment participants had to pay PRSI on anything over the €352 threshold.
Mr Deasy said that Mr Martin had acknowledged the error in a letter to him.
"However, in the final paragraph, the Minister states the aim of the community employment scheme remains as an active labour market programme with the emphasis on progression into employment - this is the good bit - where the employee would in any event be obliged to pay a PRSI contribution. The Minister accepts a mistake has been made, but he is loath to admit it." Mr Deasy was speaking during the debate on the Social Welfare and Pensions Bill.
Charlie O'Connor (FF, Dublin South West) said that €392 million was paid out last year in rent allowances to lone parents. Young people and lone parents were being caught in the poverty trap, he added.
"The only people who benefit are landlords. I do not want to pick on landlords, but in every one of our constituencies we hear from people living in sub-standard accommodation for which a considerable amount of money is being paid through the social welfare scheme, although in the end, the families have nothing to show for it.
"This has been going on for quite some time. I suspect the Minister knows there is agreement across the political spectrum that something needs to be done about this and I hope he will be brave enough to grasp that nettle," Mr O'Connor said.
Joanna Tuffy (Labour, Dublin Mid West) said that when it came to protecting the incomes and living standard of pensioners, lone parents, home carers and those seeking work, the omissions from the Bill were a catalogue of missed opportunities.
"A functioning social welfare system should protect the most vulnerable in society, supporting their search for employment where appropriate and ensuring a decent standard of living. Our social welfare system, even after a decade of phenomenal growth, fails on both counts," she said.