Presuming this is in the current Tax year ie since 1st January get a p45 from your former employer. if you are still unemployed bring it into your local Tax Office with a P50 form and Revenue will refund the Tax. if on the other hand you have resumed employment bring the P45 into your current employer and the E tax will be refunded by the new employer in your pay slip once a Tax credit form has been issued to the new employer by Revenue.