Mortgage overpayments: reduce the term or the payment?
When you make a lump-sum mortgage overpayment (amortización anticipada), the bank asks a question many borrowers have never considered: do you want to lower the monthly payment, or shorten the term? Same money in, very different results. This guide works through the numbers so you can choose deliberately.
Why the two options are so different
Spanish mortgages use the French amortisation system: a constant monthly payment in which, at the start, most of each euro goes to interest and only a little to principal. Interest each month is simply the outstanding balance times the monthly rate. So anything that keeps the balance lower for longer — or keeps you paying for fewer months — cuts total interest.
- Shorten the term (reducir plazo): your payment stays the same, but the loan ends earlier. You keep attacking the principal at the original pace with a smaller balance, so the debt collapses faster. This option always saves more interest.
- Lower the payment (reducir cuota): the term stays the same and the payment is recalculated on the smaller balance. You save some interest, but you stretch the smaller debt over the full original term, so the saving is much smaller. What you gain instead is monthly liquidity.
Worked example: €150,000 over 25 years at 3 %
The monthly payment is €711.32 and total interest over 25 years, with no overpayments, is about €63,395. After two years of payments the outstanding balance is roughly €141,692. Now you overpay €10,000, leaving €131,692:
- Option A — shorten the term: you keep paying €711.32. The remaining 276 months shrink to about 249: the loan ends 27 months (2.2 years) early and lifetime interest drops to about €54,100 — a saving of roughly €9,300.
- Option B — lower the payment: the term stays at 276 remaining months and the payment drops to about €661 — €50 less per month. Lifetime interest is about €59,500: a saving of roughly €3,900.
Same €10,000, but option A saves about 2.4 times more interest than option B. The earlier in the life of the loan you overpay, the bigger the gap, because that is when the balance — and therefore the interest — is largest.
Timing matters more than amount
An overpayment in year 2 works on a large balance for many remaining years; the same overpayment in year 20 mostly replaces principal you were about to repay anyway. If you expect to receive a windfall (bonus, inheritance, sale of property abroad), overpaying early is where the compounding works hardest in your favour. Conversely, in the final third of the loan, the financial case for overpaying weakens and alternatives — like investing the money — become relatively more attractive. Our article on compound interest explains the flip side of the same mathematics.
Early-repayment fees in Spain
Since the 2019 mortgage law (Ley 5/2019), early-repayment fees on new loans are capped and can only be charged if the bank actually suffers a financial loss. The caps differ for variable and fixed loans, and many contracts set fees below the legal maximum or waive them entirely. Two practical rules: read your deed (escritura) for the exact percentage, and remember the fee applies to the amount repaid, not the whole balance — a small fee rarely erases the interest saving, but it slightly favours fewer, larger overpayments over many tiny ones.
When to choose each option
- Shorten the term if your monthly budget is comfortable and your goal is to minimise total interest and be debt-free sooner. This is the mathematically superior choice in almost every scenario.
- Lower the payment if your budget is tight, your income is about to drop (parental leave, career change), or you hold a variable mortgage and want a buffer against future Euribor rises. €50/month of breathing room has real value that a spreadsheet does not capture.
- A hybrid strategy: some borrowers lower the payment for security, then keep voluntarily paying the old amount — replicating most of the term-reduction saving while retaining the right to fall back to the lower payment if life gets complicated. Check whether your bank processes this without fees.
Should you overpay at all?
Overpaying yields a guaranteed, tax-free "return" equal to your mortgage rate. At 3 %, that competes respectably with low-risk savings; holders of older loans at 1 % may do better keeping an emergency fund and investing. Also consider whether the money should first clear more expensive debt (consumer loans, credit cards) — those rates always beat mortgage savings. And if you are still choosing your loan, the fixed-versus-variable decision interacts with your overpayment plans: see fixed or variable mortgage in 2026.
Frequently asked questions
Do I have to choose one option forever?
No. Each overpayment is a separate transaction, and you choose term or payment each time. Many people mix both across the life of the loan.
Is there a minimum overpayment amount?
Legally no, but some banks set operational minimums (often a few hundred euros). Check your contract or app — many Spanish banks now process overpayments online in minutes.
Does an overpayment change my interest rate?
No. It only changes the balance, and consequently either the term or the payment. On a variable loan the rate still tracks Euribor at each review.
How do I know the exact saving for my own mortgage?
Run your real numbers — balance, rate, remaining term — through the simulator and compare both options side by side before instructing the bank.
Simulate your mortgage, test overpayment scenarios and compare the full amortisation schedules.
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