Charities struggling to attract donations want to be allowed to fundraise through ATMs.
They have reported falls in fundraising revenue of 20pc to 40pc in the past few years.
"All Irish charities have suffered a huge drop in donations from the public," Dermot Kirwan, spokesman for Friends of the Elderly said.
"Many have had to cut down on services, leaving thousands of vulnerable people without the vital supports."
The charity is urging the Government, which now has control of most of the retail banking system, to allow people to 'give in an instant' by making a donation when they use an ATM. Donations made in this way are listed on bank statements, which can later be used to claim tax relief.
Ruth Guy, from Barnardos said it was finding it increasingly difficult to raise funds as donors' personal circumstances deteriorated.
"A lot of them (donors) are calling us and saying they can't afford to continue to give us money, which is completely understandable," Ms Guy said.
Other charities that provide aid at home and abroad are feeling the pinch.
"The public mood is fragile. People are worried about their own circumstances," Eamonn Meehan from Trocaire said.
"There is no doubt that after the Budget, we will all have less money, so I think for organisations like Trocaire, it is a worrying time."
Charity experts also said there was now a "jaded" reaction to international humanitarian disasters.
Haven, a charity that builds homes in Haiti, said there had been a very positive response from donors to the appeal after the earthquake in the poverty-stricken country, but just €13,000 was raised for a later appeal following the outbreak of cholera there.
"I would put it at about 60pc to 70pc (of people being) jaded and I would put the rest that they just don't have the money," Haven's operations director Anne Maguire said.
Mr Kirwan believes that the 'give in an instant' option of donating to charities though cash machines will be welcomed by the public and will be a big boost to charities.
He also called on shops to encourage customers to 'round up the euro' when using a debit or credit card, with the extra money going to charity.