The Scottish Government has said it will implement several of the recommendations made by an expert group it set up to look at welfare in the event of a Yes vote.
These include abolishing the current benefits sanctions system and work capability assessments, ending the so-called ''bedroom tax'' and increasing the carer's allowance.
Nicola Sturgeon was pressed on how much it would cost an independent Scotland to reform the system when she appeared before the Scottish Parliament's Welfare Reform Committee.
Committee convener Labour MSP Michael McMahon, asked: "Do you accept that there will be cost implications? Some people have suggested about £350 million looking at the recommendations of the committee. That figure has been bandied about. Do you recognise those figures?
Ms Sturgeon said: "I don't know where that particular figure comes from so, no, I don't accept that figure.
"The report is very open about some of the cost implications of some of the proposals it's making.
"Much of what the report was talking about is how we use current resources better, particularly to help those who are furthest away from the labour market into work."
Ms Sturgeon said the welfare system in Scotland is "almost entirely" delivered in Scotland and by staff in Scotland.
On set up costs, she added: "Without wanting to put words in the expert group's mouth, I think what they were saying is they think that is broadly neutral."
Labour MSP Jackie Baillie said: "It's been suggested by experts that there would be set up costs for an IT system. The suggestion was that that was £300-400 million. Is that a figure that you would embrace?"
Ms Sturgeon said: "I'm not going to put a figure on that."
The Deputy First Minister said she could not provide more clarity as the UK Government was "unwilling" to have discussions with the Scottish Government on the issue.
She said: "I'm perfectly ready and willing to go and talk to the UK Government , I'm happy to clear my diary and do that at the point of their choosing if they want us to be able to bring more clarity."
SNP MSP Kevin Stewart said he had encountered "real fear" from people about work capability assessments in particular.
He said: "I would argue trust has broken down and been replaced by fear in many places because of the Westminster Government's welfare changes."
Ms Sturgeon said: "The expert group was very clear about its views around the breakdown of trust and the fact that many people who are in the broader social security system feel very scared and uncertain. That's going to take time to rebuild.
"We've got to make sure that these people are dealt with in a system that is personal, that is respectful of their dignity and doesn't create this climate of fear and uncertainty that exists for a lot of disabled people right now."