Less than one fifth of deceased patients' families, illegally charged for their nursing care, have sought compensation from the State.
New figures show that less than 10,000 of the 55,000 estates have made claims under the Health Repayment Scheme.
It's believed people are being put off by a fear of an audit by the Revenue Commissioners.
Dan Boyle of the Green Party says they should make a statement explaining the tax liabilities for families
"It could mean that many of the people who are entitled to these payments are holding back in case they might lose more than they might gain," he said.