The abolition of cheques will push elderly people back into hoarding cash at home, campaigners have said.
The proposed winding down of the cheque system by 2018 is being discussed by an influential committee of MPs.
The Treasury Committee heard from campaigners who argued that older people would have to rely on others if the payment system ended.
The payments industry says that the use of cheques is in terminal decline and alternative methods should be found.
Teresa Perchard, policy director of the Citizens Advice Bureau, told the committee that 340,000 people still received their benefits by cheques through the post and a number of cheques would still be in circulation in 2018.
She added that the people who still only used cheques were dispersed across the UK and were not refined to a specific group.
Jane Vass, of Age Concern and Help the Aged, said that there could be a security issue if cheques were to be phased out.
"This would encourage people to return to cash. We have concerns about large amounts of money kept at home," she said. "Older people will be forced to depend on others."
"We have not seen specific, clear, fleshed-out alternatives."
The committee was also told that there were worries about consumers and small businesses facing higher charges with any new technology.
The body that oversees payments strategy, the UK Payments Council, announced in January that cheques would be phased out by October 2018, but only if adequate alternatives had been developed.
The council set the 2018 date in an attempt to encourage the advance of other forms of payment.
The first cheque was written 350 years ago, but the council said there should be "no scenario" for using cheques by 2018. A final review will come in 2016.
Louise Richards, of the Institute of Fundraising, said that 6.4 million people aged over 65 did not have access to the internet. This would prevent them using some other payment methods.
The Treasury Committee discussed the make-up of the Payments Council and whether it had a vested interest in the decline of the cheque.
Geoff Holland, chief executive of the British Cheque and Credit Association, said that only eight of the 28 members of the council offered current accounts with a chequebook. Other members were part of the electronic payments industry, he said.
Committee chairman John McFall MP questioned whether the "terminal decline" of cheques was in fact a "fudged, managed decline".
Paul Smee, chief executive of the Payments Council, said that the end of cheques would save businesses £750m and save banks £200m.
However, the committee continually pressed him on the fact that he had not produced any figures that would quantify the costs of abolishing cheques.
Following a period of hard questioning and an accusation that the figures were "contrived", the Payments Council was asked to produce an accurate cost-benefit analysis of the end of cheques.
Many stores - including all the major UK supermarket chains - have chosen to stop accepting cheques as shoppers turn to debit or credit cards, or stick with cash. Cheques are also the most expensive form of transaction for shops.