Taxation of Redundancy Payment

I’m wondering how this works?
I’ve calculated approx €9k of my severance package is taxable but is it seen as income for that month in which case I would pay 40% tax on it?
Do I have to wait until the end of the year to reclaim any overpayment, I very much suspect if it was taxed at 40% there would be an overpayment

Have you read these already?
There are also some existing threads on this topic that you should be able to find using the search facility.