Quick answer
- Overpaying produces a return similar to mortgage interest avoided, subject to mortgage terms.
- Savings preserve access to cash but deposit interest may be taxable.
- Clear expensive debt and protect an emergency buffer before locking cash into the mortgage.
- The best split depends on rate, tax, risk, access and near-term plans.
On this page
The basic comparison
Paying €1 off mortgage capital avoids future interest at the mortgage rate while that €1 would otherwise remain outstanding. Keeping it in savings earns the savings rate and keeps the money accessible. Compare the mortgage rate with the savings return after tax and fees, but also value access to cash.
For an Irish-resident individual, DIRT is generally deducted from deposit interest at 33% unless an exemption applies. A 3.00% gross deposit rate is therefore about 2.01% after 33% DIRT alone, before any PRSI liability or account fees. Against a 4.00% mortgage, overpayment has the stronger simple rate comparison, but liquidity can still make saving the safer decision.
When saving first is usually safer
- You do not yet have an accessible emergency fund.
- You expect maternity leave, a job change, repairs, education or another major cost.
- Your income is variable or one household income may stop.
- The fixed mortgage would charge for the proposed overpayment.
- You need funds for a known refinancing or property expense.
CCPC guidance commonly frames an emergency fund around three to six months of essential costs or income. The right amount depends on household stability.
When overpaying becomes more attractive
Overpayment becomes easier to justify when the emergency reserve is secure, expensive short-term debt is cleared, no break fee applies and the after-tax savings rate is materially below the mortgage rate. A long remaining term gives an early capital reduction more time to avoid interest.
Confirm whether the lender will shorten the term or lower the payment. Keeping the normal payment usually captures more term and interest saving.
Do not ignore pension and other goals
Mortgage-versus-savings is not always the complete choice. Pension contributions may receive tax relief subject to eligibility and limits, while investments carry risk and are not equivalent to guaranteed deposit savings. Near-term goals should not be funded with money that may fluctuate or become inaccessible.
This guide provides a comparison framework, not personal investment advice. Use regulated advice where the decision involves pensions, investments or tax planning.
A balanced decision process
- Keep the next month of bills and an emergency reserve accessible.
- Compare expensive debt before the mortgage.
- Get the lender overpayment allowance and fee in writing.
- Compare mortgage rate with the savings return after DIRT and account charges.
- Model the overpayment in the Mortgage Calculator.
- If uncertain, keep part of the spare cash accessible and consider a smaller overpayment; do not assume money already overpaid can be withdrawn.
Worked comparison: the same €10,000 over one year
Assume a €250,000 capital-and-interest mortgage, 20 years remaining and a 4% annual interest rate. You have €10,000 spare after keeping a separate emergency reserve. Compare applying it immediately to mortgage capital with placing it in a deposit paying an illustrative 3% gross annually. These are assumed rates, not current product offers.
For both options, keep the normal mortgage payment of approximately €1,514.95 per month and compare balances just after the twelfth payment. Assume the mortgage rate remains 4%, monthly interest at 4% ÷ 12, no overpayment charge, and annual savings interest credited at year-end. The deposit example deducts 33% DIRT, assumes no exemption, no PRSI liability and no account fees. Amounts below are rounded to cents; the mortgage calculation retains the unrounded formula payment.
| After 12 months | Overpay €10,000 | Save €10,000 |
|---|---|---|
| Mortgage balance | €231,261.54 | €241,668.96 |
| Separate deposit balance | €0.00 | €10,201.00 |
| Mortgage debt less this deposit | €231,261.54 | €231,467.96 |
Overpaying leaves the net debt position €206.42 lower under these assumptions. That difference is not €10,000 of new profit: both options started with the same money. Saving keeps the deposit available subject to account access terms; the overpayment is in home equity. Other assets and your separate emergency reserve are unchanged and excluded.
Reproduce the comparison
- Mortgage balance reduction after 12 months: €10,000 × (1 + 0.04 ÷ 12)12 = €10,407.42. With the same repayments, this comprises €10,000 of extra principal repaid plus €407.42 of interest avoided.
- Deposit interest: €10,000 × 3% = €300 gross; €300 × 33% = €99 DIRT; net interest is €201.
- One-year difference: €407.42 avoided interest − €201 net deposit interest = €206.42. Do not add the original €10,000 to the gain or add avoided interest twice.
The simple 3% × (1 − 33%) = 2.01% deposit comparison is DIRT-only. Revenue confirms that PRSI can also apply to deposit interest; USC does not. Check your own liability, exemptions, fees and interest-crediting terms before using the example for a decision.
Use the same five-year horizon for both options
If both rates remain unchanged, the monthly payment stays the same, and net savings interest is reinvested annually, after five years the mortgage balance difference is €10,000 × (1 + 0.04 ÷ 12)60 = €12,209.97. The deposit becomes €10,000 × (1.0201)5 = €11,046.22. The unrounded difference is €1,163.74 in favour of overpayment. This is a five-year balance comparison, not total lifetime mortgage interest saved. Changing rates, withdrawals, charges or a different repayment arrangement changes the result.
In the Mortgage Repayment Calculator, enter €250,000, 4% and 20 years; use a €10,000 one-off lump sum with zero extra monthly payment. Its overpayment result measures the whole remaining loan. Do not compare that lifetime saving with only one year of deposit interest. Use the overpayments guide for the repayment mechanics.
Fees, emergency cash and what to ask the lender
A fee must come from the same cash budget
Suppose the lender quotes an illustrative €300 charge and your total available cash is still €10,000. Pay €300 in fees and only €9,700 into mortgage capital. With the same loan assumptions, the 12-month balance reduction is €9,700 × (1 + 0.04 ÷ 12)12 = €10,095.19. The deposit alternative still ends at €10,201, so saving is €105.81 ahead over this year.
Do not model a €10,000 overpayment plus a fee paid from unspecified extra money. The €300 is an example, not a lender tariff. Get the permitted amount, actual charge and application date in writing. The CCPC explains fixed-rate restrictions and applying overpayments to capital.
Keep emergency money outside the comparison
For an illustrative household with €2,500 monthly essential spending, a chosen six-month reserve is €15,000. If a further €2,000 repair is already planned and accessible savings total €27,000, the amount available to compare is €27,000 − €15,000 − €2,000 = €10,000. Six months is a planning choice here, not a requirement that suits every household. Account for income security, dependants and upcoming costs before choosing your reserve.
The €206.42 no-fee advantage does not replace access to €10,000 in an emergency. Borrowing it back later can require a fresh credit decision and a different rate. A split can preserve some cash, but the amount already overpaid is not automatically withdrawable.
Confirm the repayment treatment before paying
- Will the extra payment reduce capital immediately, rather than remain in a credit or suspense account?
- Will the normal payment continue, shortening the term, or will the lender lower the monthly repayment?
- What amount is permitted without a charge, and is that allowance already partly used?
- When does the current rate end, and what rates should you test afterwards?
The worked comparison keeps monthly payments unchanged. If the lender lowers them, include the released monthly cash on the overpayment side and state whether you spend or save it. Otherwise the two options no longer have equal cash outgoings. Obtain the lender’s schedule and compare both choices over the same dates.
Frequently asked questions
Is it better to overpay a mortgage or keep savings?
Overpaying may win mathematically when the mortgage rate exceeds the after-tax savings rate, but savings provide access and emergency resilience.
What savings rate should I compare with my mortgage?
Use the rate you can actually receive after DIRT, fees and any access conditions, not only the advertised gross rate.
How much emergency savings should I keep?
A common planning range is three to six months, adjusted for essential spending, income security and expected costs.
Should I overpay while on a fixed rate?
Only after checking the permitted amount and any early repayment charge.
Can I withdraw a mortgage overpayment?
Usually not on demand. Treat it as locked into home equity unless your mortgage terms explicitly provide a redraw or flexible facility.
Should I clear other debt before the mortgage?
Higher-rate unsecured debt often costs more, but check repayment charges and preserve an emergency buffer.
Sources & references
Related calculators
Use these tools for the numbers behind this guide.