According to the Revenue's info on the Income Levy, as long as you have a medical card for even part of the year, you pay no Income Levy for all the year. But what if you worked Jan-May, got laid off, applied for and got a Med Card in June, does that mean you can get a refund for the Income Levy you paid from Jan to May? If so, can you get a mid-year refund?
From what I remember of the FAQs on the Income levy, claims for overpayment of the Income Levy are made at the end of the tax year (like refunds of tax).