Social Justice Ireland has called for social welfare rates to rise by €9 a week.
The think tank has warned a rise in poverty is "inevitable" unless there is a rise in core social welfare rates.
It is also urging the Government to equalise Jobseeker's rates for young people under 26, and to introduce a universal state pension.
It is part of a pre-budget forum in Dublin Castle, hosted by Social Protection Minister Regina Doherty.
The group is proposing a €9 increase in core social welfare payments to maintain their benchmark in Budget 2020.
It is also suggesting a €5 increase in the living alone allowance, an increase of €20.50 in the domiciliary care allowance and an increase of €300 in the carer's annual support grant.
Eamon Murphy, an economic and social analyst at Social Justice Ireland, said: "One of the least justifiable welfare policies pursued in recent years was the increase in the age of eligibility for full Jobseeker's Allowance payments to 26 years.
"While just one of many examples of how young people were disproportionately affected by austerity measures, it is one of the most clearly discriminatory, with little obvious benefit.
"Government should move to equalise Jobseeker's rates for under 26s with the rest of the population in Budget 2020".
Research and policy analyst Colette Bennett said: "A lesson from past experiences of economic recovery and growth is that the weakest in our society get left behind unless welfare increases keep track with increases elsewhere in the economy.
"The €5 increases in core welfare payments in Budgets 2017, 2018 and 2019 were very welcome, but were not enough to keep pace with the benchmark. A further increase of €9 in Budget 2020 is required to address the growing gap between welfare payments and average earnings.”
However, the Minister for Social Protection said raising the old age pension by €18 a week over the next two years would be "imprudent".
Age Action Ireland has called on the Government to commit to a €9 a week rise in the coming budget, saying many older people are struggling financially because the state pension has not increased in line with inflation over the last 10 years.
Minister Doherty said an €18 increase is not a good idea with Brexit on the horizon.