Social Justice Ireland say the poorest people in society need to be protected from the potential economic shock of Brexit.
The Government is set to release its budget for 2020 on Tuesday.
However, the Irish Fiscal Advisory Council is warning Britain's exit from the EU could hit the State's tax take hard.
Dr Seán Healy, chief executive of Social Justice Ireland, said social welfare payments need to go up to protect the poorest from the effects of Brexit.
He said: “We are one week away from a Budget that is being shaped by Brexit. It is vital that available resources are prioritised on protecting communities, jobs and the vulnerable.
“In practical terms this means investing in communities, in indigenous enterprise and jobs creation, and it means ensuring that those who are reliant on social welfare are not left even further behind.”
Michelle Murphy, Research and Policy Analyst at Social Justice Ireland, said: "In order to protect the most vulnerable while preparing for Brexit we must ensure that we close the gap between current minimum social welfare rates and the benchmark of 27.5% of average earnings.
"This gives an indication of just how important social welfare rates are in protecting the most vulnerable in our society. We should not lose sight of this as we face into a period of potential economic upheaval”
Dr Healy said: "Poverty will rise if welfare rates do not keep pace with these changes in Budget 2020. This is why Social Justice Ireland is calling for an increase of €9 in minimum social welfare rates in Budget 2020.”