The Labour Party called on the Minister for Finance to introduce a minimum effective tax rate and form a commission on tax reform in the upcoming Budget.
Setting out the party's budget priorities today, Labour's finance spokeswoman, Ms Joan Burton, said Mr Cowen must target those on lower incomes by increasing tax credits and social welfare measures.
Labour's wants to see an expansion in the standard rate band by at least €2,750 and the PAYE credit by at least €280.
In social welfare, Labour is calling for the abolition of the means test for the carers' allowance, expansion in medical card eligibility and expanded paid parental leave including an extra eight weeks of paid maternity leave.
Labour said Mr Cowen must also increase the lowest rate of social welfare payment by at least €14 per week and finish the Government's programme of increases in child benefit.
The Government Chief Whip Mr Tom Kitt issued a strong defence of taxation policy in reaction to Labour's statement.
He claimed there had been huge improvements for PAYE earners since 1997 at both the lower end and for those on the average industrial wage.
He said Labour had had made "absolutely no acknowledgment" of the progress made for those on lower incomes in recent years and accused the party of ignoring the plight of the less well-off and pensioners.