The IFA has strongly rejected suggestions that Ireland should examine alternatives to the historical basis used for calculating the Single Farm Payment (SFP).
Agriculture Minister Brendan Smith recently indicated that the current regime for establishing SFP entitlements would be on the agenda when the details of CAP post-2013 are renegotiated.
However, IFA president Padraig Walshe said Minister Smith should make it abundantly clear to his European colleagues that he is not prepared to give away one cent of Irish SFP funds.
He said SFP post-2013 must continue to be directed to supporting active farmers.
"Ireland's Single Farm Payment budget must be fully protected and this means protecting the historical basis of calculation," Mr Walshe said.
"Alternatives, which would deliver a reduced level of Single Farm Payment for Irish farmers must be rejected."
While SFP entitlements to Irish farmers are based on payments received in the three reference years of 2000, 2001 and 2002, a number of eastern European countries work off a flat payment per hectare farmed.
The EU commission wants this system extended across the union but this is strongly opposed by the Irish farm organisations.
Mr Walshe pointed out that an annual allocation of €1.5bn for the SFP and €400m for rural development, as well as the continued use of the historical basis for calculating SFP entitlements, were key planks of an IFA submission to Minister Smith on the future structure of the CAP post-2013.
Talks on the overall EU budget and proposed funding for CAP post-2013 are expected to gather pace during the year.