The Society of St Vincent de Paul says it expects to spend up to €50m this year helping people in need.
It says calls for help to its offices in Dublin are up 40% on this time last year, most of them coming from families with children.
Society President Mairéad Bushnell said she was concerned but not surprised by the increased demand for its services.
She said more than 1m people in Ireland lived in or on the edge of poverty.
People who up until last year had donated money to the charity are now coming to it looking for help, according to Ms Bushnell.
She said the dire situations have started, with some families in horrendous debt.
The society said people earning more than €85,000 a year would be willing to pay a levy on their incomes for a limited period to protect the most vulnerable from increasing levels of poverty.
The society's vice president Professor Monaghan also urged the Government to begin making up its revenue shortfall by reviewing tax breaks it had extended to property owners and certain areas of private spending.
He also said the poor should benefit from the state's increased excise revenue generated by rising oil prices.
Meanwhile, over 100 groups represented by the Disability Federation of Ireland have challenged the Government over almost two years of cutbacks.
DFI chief executive John Dolan said the state should refund €83m that it has diverted from people with mental health problems and other disabilities.
Tomás Thompson of the Cystic Fibrosis Association of Ireland said many of its members were losing out on diet, fuel and telephone subsidies, which they rely on to keep them out of hospital.