It depends - you could shorten the term of the mortgage significantly or reduce your outgoings, but on the other hand you may be able to get good deposit rates. Have a look at the mortgage calculator here http://www.jeacle.ie/mortgage/ to see what effects making a lump sum payment would have, and check the financial best buys forum to see what deposit rates might be available.I have about €110k outstanding on my mortgage: if I were to put €30k into it would it make a significant dent in my repayments? Or should I stick that money away in a notice account?