Yes, it's mandatory. The Irish High Commission needs a total of 6.0 bands for UG classes and a total of 6.5 for PG visa courses. But there are chances of your IELTS test being wavered in case you've scored remarkably well in your 12th class english exam. admissify.com is amongst very few international education consultancies which helps you undertake the application procedure in your best interest. i had 95% in my english subject in 12th class, and they helped me skip IELTS for my admission in Trinity college, Dublin.