They did the exact same thing to me last year. After wasting good tax payer’s money and harming the environment my sending me Form 12 in the first place. I just filled out the 'exact same' information on the Form 11 and sent it back to them. A total waste of time and effort. Honestly, the only reason I would think of was that Form 12 is handled by your local tax office and Form 11 is processed centrally in Limerick and they were too lazy to handle it in the local office.