I'm currently in the process of buying a house, with an AIB mortgage with a long term. I currently save a large amount every month. My plan is to overpay the mortgage substantially, while the relatively low repayment from having the long term gives me flexibility in case interest rates rise dramatically in the coming years. From a practical point of view, how does the overpayment work? Can I just transfer money whenever I feel like it with the online banking system, or do I need to commit to a monthly overpay or make occasional lump payments? Also, does it make more sense to reduce mortgage term or monthly payments with an overpayment? I'd obviously like to pay it off as soon as possible, but on the other hand I am a little concerned that rates will rise substantially at some point, so reducing the capital and leaving the term alone would be comforting from that point of view.