Calling all brainboxes - please help me with a PRSI Calculation

I think it has to be calc on the monthly basis and if any overpayment at the end of the year you do have to apply for a refund. Daft but it wouldn't be the fitst daft element about this tax.

True the calc is on a monthly basis, but as the payment in question is in December (the last month of the year) and if you know the total gross annual salary to be €120,000, I would be inclined to submit the correct PRSI + health levy for the year rather than make the calc on a monthly basis and then apply for the refund.

However, if this was in the middle of the year I would use the monthly basis calc.
 
I would be inclined to submit the correct PRSI + health levy for the year rather than make the calc on a monthly basis and then apply for the refund.

I think the employer makes the returns so would have to calc on a monthly basis even if the payment is at the end of the year and the employee would have to apply for the refund.

I am open to correction in all of this. I am no expert.