Fianna Fáil is urging the government to give greater legal protection to mortgage holders at the former Irish Nationwide.
IBRC is selling off its mortgage book later this month and could leave up to 13,000 mortgage holders without any consumer protection.
The assets and liabilities of Irish Nationwide were transferred to Anglo Irish Bank in 2011 - which is now IBRC.
Last week, one of the Special Liquidators of the former Anglo Irish Bank admitted that a deal they reached on the Code of Conduct on Mortgage Arrears has no legal standing.
The two final bidders for the loan book held by the Irish Bank Resolution Corporation (IBRC) agreed on a voluntary basis to adhere to the Central Bank guidelines, but this is not legally binding.
Fianna Fáil is bringing forward a Bill which would force anyone buying the loans to honour the Central Bank Code of Conduct for mortgage arrears.
Finance spokesman Michael McGrath is urging the government to support the bill when it goes to a Dáil vote tomorrow night.