Benefits changes: Universal Credit system warning
Seventy organisations involved in the benefits system have raised concerns about a government overhaul.
The Universal Credit aims to make the system simpler by replacing five work-based benefits with one benefit.
The groups are worried about moving to monthly payments, access to an online system and whether a new IT system will be ready by an October 2013 deadline.
The government says managing the system online will save money, and that the new benefit is set to come in on time.
Ministers have said they are determined to reform the system, so it pays people to work rather than claim benefits.
Written evidence, seen by BBC Radio 4's The World This Weekend, was submitted to the House of Commons Work and Pensions Committee by organisations representing councils, charities, trades unions, business groups and housing organisations.
The Women's Budget Group is among those expressing concerns about new monthly payments, saying "many on low incomes in work have wages and/or benefits and tax credits paid more frequently, which matches common budgeting patterns for those on low incomes".
The group, which works towards "a gender equal society", adds: "Women are likely to be hit harder, as in low income families they tend to make more frequent purchases that will be squeezed as money is stretched."
The BBC's Chris Mason says there are concerns that a policy of paying the Universal Credit to just one person in a household could, in some instances, upset the family dynamic - potentially putting that individual in a position of considerable power and influence.
And Gingerbread, the charity for single parents, asks: "What consideration has been given to providing grants to cover a shortfall when transitioning from fortnightly to monthly payments, rather than claimants having to rely on budgeting advances or 'pay-day loans' which need to be repaid?"
The Local Government Association, meanwhile, is among groups concerned that there is "a real risk that the central government Universal Credit IT systems will not be ready on time".
And the CBI business organisation says: "The new system's tight delivery timetable, coupled with low awareness among companies, is a risk to business and to the implementation of the Universal Credit."
'Rigorous testing'
The government's push for claimants to access benefits online is also questioned by some groups.
Community charity Citizens Advice warns that the Universal Credit system "risks causing difficulties to the 8.5 million people who have never used the internet and a further 14.5 million who have virtually no ICT skills".
However, the submissions also show that many organisations acknowledge the government's motivations for reform are sound.
Ministers insist the timetable for the introduction of Universal Credit remains on track to begin in October 2013.
It will be phased in over a number of years, with eight million households signed up by 2017.
In its own submission to MPs, the Department for Work and Pensions says rigorous testing of the IT system is already under way.
It says those who struggle to use the online system will still have access to face-to-face help and telephone assistance.
And it adds that managing Universal Credit online makes sense as it saves money - and says most jobs do now require computer skills.
Are you on benefits? What do you think about plans to digitise the benefits system? Please send in your comments using the form below.