What rate of tax applies in the State on my foreign deposit interest?
A. This depends on the location of the financial institution. If it is located in another EU country, tax on the gross interest earned is due at the same rate as tax on Irish deposit interest income – 20% up to 31st December 2008, 23% for the period 1st January 2009 to 7th April 2009 and 25% from the 8th April 2009. In order to avail of this treatment, you must make a timely and accurate return of the foreign deposit interest and pay any tax due by the prescribed return filing date for the year concerned.
If the interest is earned from a financial institution outside the EU, tax is due at your marginal (highest) rate of tax.
Prior to 1 January 2005, all foreign deposit interest income, including interest from another EU country, was taxable at the marginal rate – that is, the higher or highest rate at which you pay income tax. Since 1 January 2007 the higher rate of income tax in Ireland has been 41%.[\QUOTE]
see here [broken link removed]