Married couples with a particular high/low income combination are paying more tax than their counterparts whose income is more evenly balanced. The difference could amount to £660 per year on a joint income of £40,000.
The discrepancy, which was highlighted by Fine Gael TD Mr Gay Mitchell last week, arises from the individualisation of the tax bands and the widening of the standard tax band rate.
The Minister for Finance, Mr McCreevy, confirmed that a couple earning salaries of £25,000 and £15,000 would pay £5,000 in tax, while a couple earning £32,000 and £8,000 would pay £5,660.
In Budget 2000, the standard rate tax band for a married couple with both spouses working was set at £40,000, double that of a single person.
In his response to Mr Mitchell, Mr McCreevy explained that the £40,000 band for the two-income couple was transferrable from one working spouse to another, subject to a maximum band of £29,000 for either spouse.
The £29,000 limit arises because that is the maximum standard rate band that applies to one-income couples. A spokeswoman for Mr McCreevy said there had to be a cut-off point for transferability for reasons of fairness.
The Minister said the policy of widening the standard rate band and putting it on a per person basis was designed primarily to meet the Government's commitment to ensure that 80 per cent of taxpayers should not pay the higher rate of tax.
Mr McCreevy said the best way of achieving this was by restructuring the band so that people were taxed on what they earned, regardless of marital status.