A recurring extra payment or a one-off lump sum both go straight against principal, so every euro overpaid stops accruing interest for the rest of the term. This calculator runs your actual repayment schedule month by month, with and without the overpayment, and shows the real interest saved and time shaved off.
Your standard monthly payment is the ordinary annuity formula on your principal, rate and term. Each month, interest accrues on the remaining balance, the standard payment covers that month's interest plus a slice of principal, and any overpayment (recurring, or a lump sum applied in the year you choose) comes straight off the remaining balance. A lump sum applied early has more months left to stop accruing interest on, so it saves more than the same amount applied later — timing matters as much as the amount.
Whichever gets money against the principal sooner. A recurring overpayment starts working from month one; a lump sum only starts saving from the month you pay it. If you have the lump sum today, paying it now generally beats waiting to build it up through smaller monthly overpayments — try both in this calculator with your own numbers.
Most Irish variable-rate mortgages allow overpayments with no penalty, but many fixed-rate deals cap penalty-free overpayments (commonly around 10% of the balance a year) or charge a breakage fee above that. Check your own mortgage terms before overpaying — this calculator assumes the whole overpayment is applied penalty-free.
Not necessarily — it depends on your mortgage rate versus what you could realistically earn investing that money instead, and on your appetite for risk. A mortgage overpayment is a guaranteed, tax-free return equal to your mortgage rate; investing is not guaranteed. Compare your specific rate against realistic investment return assumptions before deciding.
Figures are estimates for informational purposes only, based on the assumptions you enter, and are not tax advice. Consult a tax advisor or Revenue.ie before making financial decisions.