NRE and NRO interest when you are an Irish tax resident

In India, interest on an NRE account is exempt under Section 10(4) while you hold non-resident status, so India charges nothing and deducts no TDS. NRO interest is taxable, with TDS under Section 195 at about 31% by default, which the India-Ireland treaty caps at 10% if you file a tax residency certificate and Form 10F with the bank before the interest is paid. So on the Indian side, NRE is untaxed and NRO is taxed at up to the treaty rate.

For a non-domiciled Irish resident, both NRE and NRO interest are foreign income under the remittance basis, so they are taxed in Ireland only to the extent you bring them into the country. Interest that accumulates in your Indian accounts and stays there is outside the Irish charge, which for most Indians in Ireland means Ireland does not tax it at all.

For an Irish-domiciled resident it is different, and this is where the tax-free-NRE idea fails. A domiciled resident is taxed on the interest as it arises, wherever it sits, at their marginal income-tax rate. So NRE interest, tax-free in India, is fully taxable in Ireland for a domiciled resident, and because India levied no tax on it, there is no India tax to credit, so the Irish charge stands in full. NRO interest is taxable in Ireland too, but there the India tax, capped at the treaty rate of 10%, is credited against the Irish tax, relieving most of the double charge.