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Overpayment calculator
Mortgage overpayment calculator explained for Ireland
An overpayment calculator illustrates how extra monthly or lump-sum payments could change mortgage interest and the payoff date.
Page checked: 21 October 2026
Two common overpayment types
Monthly overpaymentAdd a regular amount to each scheduled repayment.
Lump sumMake a one-off extra payment against the mortgage balance.
What the result means
The illustration can show a shorter term, a lower balance and lower total interest. The actual effect depends on how your lender applies overpayments and whether your mortgage contract includes limits or charges.
Test your scenario
Use Reduce The Damage to compare a monthly overpayment or lump sum against the original mortgage.
Use Reduce The Damage to compare a monthly overpayment or lump sum against the original mortgage.
Sources & assumptions
Central Bank mortgage-measure limits and Revenue stamp-duty rules can change. Check the official sources before relying on an estimate.
Central Bank mortgage measures · Central Bank retail interest rates