Martin McGuinness has batted away scathing criticism that welfare powers have been "surrendered" to Westminster.
The Sinn Fein Deputy First Minister described the move as a "technicality" which saved the Stormont Executive £40 million.
He told MLAs during Question Time: "I regard it as a technicality which saved us £40 million.
"I think the SDLP need to get real. The fact that we went that technical route which has the sunset clause which ensures the powers reside in this Executive actually saves our institutions £40 million which we can put to good use on behalf of the people who sent us to this house."
The Stormont Assembly voted to allow the Government to finally roll out universal credit and other welfare changes in Northern Ireland as part of the recently agreed Fresh Start deal.
The agreement was struck between the DUP, Sinn Fein and the British and Irish governments last month and ended a lengthy stalemate on a range of issues that had pushed the region's coalition Executive to the verge of collapse.
SDLP MLA for South Down Sean Rogers asked whether the Deputy First Minister felt it was a "mistake" to "surrender" welfare powers which he claimed left the region at the "mercy of the Department of Work and Pensions" in London.
Mr McGuinness hit back, saying: "What I thought was the most interesting aspect of that was that only eight members of the SDLP bothered to turn up to vote and during the course of the debate the new party leader wasn't present during any of the debate and the new party leader didn't even vote.
"What we have done as a result of our negotiations; we have put in place a fund of £585 million to ensure that we will support those people who are worst affected by the Government cuts. We do that under the tutelage of Eileen Evason who is very experienced in dealing with all these matters.
"That is a practical contribution towards alleviating the plight of people and it is something that is nowhere else; it's not happening in England, it is not happening in Wales and it is not happening in Scotland but it is happening here."
Meanwhile, Finance Minister Arlene Foster also defended deploying the legislative consent motion which allowed Westminster to enact the welfare changes.
She said: "It was the proper method to allow us to have the debate."
After the question and answer session the SDLP rejected claims that its MLAs had not fully participated in the debate over handing welfare powers to Westminster.
A spokesman said: "The claim is simply untrue. Sinn Fein is doing all it can to distract people from the fact that it gave George Osborne the power to bring in benefit freezes and reduce the benefits cap and, unlike the SDLP, every single one of their MLAs who was able to vote supported that.
"Colum Eastwood, of course, voted against the legislative consent motion."
In a statement later, Mr McGuinness said his remarks had been "incorrect".
He said: "I have now had an opportunity to review the written voting records on welfare reform which confirm I was incorrect in my comments in the assembly today stating Mr Eastwood did not vote.
"Mr Eastwood was one of only eight of the SDLP's 14 MLAs who turned up to vote on this very important debate.
"I have instructed my officials to write to the speaker to correct this error."