Most investors underwrite a Portuguese rental at today's rate and treat the result as the answer. That is not underwriting. That is a snapshot. A buy-to-let bought at 80% loan-to-value carries thirty years of reset risk, and the distance between comfortable and cash-flow negative is usually smaller than the spreadsheet suggests.
This article models one realistic Lisbon-metro rental across seven Euribor levels, from 1.5% to 4.5%, and shows exactly where debt service, DSCR and pre-tax cash flow break. The answer for our example property is uncomfortable: it sits roughly 8 basis points from negative cash flow at the rate prevailing in August 2026.
Key takeaways: The 12-month Euribor was 2.993% on 25 August 2026. Banco de Portugal cut the maximum debt service-to-income ratio from 50% to 45% on 1 August 2026 and caps investment-purchase LTV at 80%. Our modelled 250,000 € rental turns cash-flow negative at about 3.07% Euribor.
Update, 4 October 2026: the 12-month Euribor was 3.323% on 2 October 2026 (ativos.pt), already above the 3.07% break-even calculated below. At that level, with the same 1.00% spread, our modelled 200,000 € loan costs about 11,909 € a year against 11,560 € of NOI, a cash flow of roughly -349 € and a DSCR of 0.97. The August figures below are kept as published so you can see how thin the buffer was.
Where does Euribor actually sit in 2026?
The 12-month Euribor stood at 2.993% on 25 August 2026, according to ComparaJa's daily Euribor tracker. After the sharp climb of 2022–2023 and the reversal through 2024–2025, the benchmark has settled into a narrow band rather than resuming a clear direction.
That tenor matters more than the headline suggests. The 12-month Euribor indexes roughly 31.75% of existing Portuguese mortgage contracts, which makes it the single most consequential number for leveraged landlords in the country. A 12-month index resets once a year, so a move today lands on the borrower's payment up to twelve months later — and then stays there.
Spreads add the second layer. In 2026, Portuguese lenders were pricing variable-rate housing credit at spreads between 0.60% and 1.20%, driven mainly by loan-to-value and the customer's product bundle. An investor at 80% LTV rarely gets the bottom of that range. Our model assumes a 1.00% spread, which is realistic rather than optimistic.
Citation capsule: The 12-month Euribor reached 2.993% on 25 August 2026 and indexes about 31.75% of Portuguese mortgage contracts. With 2026 spreads running between 0.60% and 1.20%, a typical investment borrower pays roughly 4.0% all-in — a level at which leverage stops amplifying returns on many Lisbon-metro rentals.
The financing rules changed in August 2026
On 1 August 2026, Banco de Portugal lowered the maximum debt service-to-income ratio (DSTI, the taxa de esforço) from 50% to 45%, measured after applying an interest rate stress shock, according to the regulator's macroprudential measures monitoring. Institutions may still write up to 10% of each half-year's lending above that limit, but only with documented justification.
The loan-to-value ceiling is the part investors most often get wrong. Banco de Portugal permits up to 90% LTV for own permanent housing and only 80% for every other purpose — which includes buy-to-let, second homes and holiday lets. There is no investor exception. If your model assumes 85% or 90% leverage on a rental, the model is not financeable.
Here is the part that rarely gets discussed. The DSTI shock is applied to your household income, not to the property's rent. A property can produce excellent DSCR and still fail the affordability test, because the regulator is protecting the borrower, not the asset. Investors with several existing mortgages hit the 45% wall long before they run out of good deals. That is a portfolio constraint disguised as a lending rule.
For the full leverage picture, see our guides to LTV in Portuguese real estate and mortgages for non-residents.
The seven-scenario model
In 2026, a typical Lisbon-metro two-bedroom rental at 250,000 € produces roughly 11,560 € of net operating income against debt service that ranges from 9,483 € to 13,626 € depending on where Euribor sits. That range — a 4,143 € swing on the same asset — is the entire risk.
The assumptions are deliberately ordinary:
| Assumption | Value |
|---|---|
| Purchase price | 250,000 € |
| Loan-to-value (regulatory maximum for investment) | 80% |
| Loan amount | 200,000 € |
| Term | 30 years |
| Spread over Euribor | 1.00% |
| Monthly rent | 1,150 € |
| Vacancy allowance | 5% |
| IMI, condominium, insurance, maintenance | 1,550 €/year |
| Net operating income | 11,560 €/year |
| Deposit + IMT + stamp duty + costs | ~63,000 € |
Now hold everything constant and move only Euribor. Annual debt service on the 200,000 € loan:
Between the cheapest and most expensive scenario, the annual payment moves by 4,143 €. On a property generating 11,560 € of NOI, that is 36% of the entire operating income — consumed or released purely by a benchmark the investor does not control.
What happens to DSCR across the range
Debt service coverage ratio is the cleanest way to read rate risk, because it collapses the whole question into one number: does the property's income cover its debt, and by how much? In our model, DSCR falls from 1.22 to 0.85 across the range — crossing the critical 1.00 line between 3.0% and 3.5% Euribor.
The full picture, including pre-tax cash flow and return on the roughly 63,000 € of equity deployed:
| Euribor | All-in rate | Debt service | DSCR | Cash flow | Cash-on-cash |
|---|---|---|---|---|---|
| 1.5% | 2.50% | 9,483 € | 1.22 | +2,077 € | 3.3% |
| 2.0% | 3.00% | 10,118 € | 1.14 | +1,442 € | 2.3% |
| 2.5% | 3.50% | 10,777 € | 1.07 | +783 € | 1.2% |
| 2.993% (Aug 2026) | 3.99% | 11,449 € | 1.01 | +111 € | 0.2% |
| 3.5% | 4.50% | 12,161 € | 0.95 | −601 € | −1.0% |
| 4.0% | 5.00% | 12,883 € | 0.90 | −1,323 € | −2.1% |
| 4.5% | 5.50% | 13,626 € | 0.85 | −2,066 € | −3.3% |
Note: cash flow is before income tax. Acquisition cost assumes IMT at second-home rates plus 0.8% stamp duty and registration. Model your own figures with the Euribor cash flow calculator.
Finding your break-even Euribor
Interpolating between the 3.0% and 3.5% rows, pre-tax cash flow on this deal hits zero at approximately 3.07% Euribor. With the 12-month rate at 2.993% in August 2026, the property sits about 8 basis points from turning cash-flow negative. Eight basis points. On an asset the owner will hold for a decade or more.
This is why gross yield is a filter, not an answer. The property above shows 5.5% gross yield — respectable by Lisbon-metro standards, the kind of number that makes a listing look like a deal. It still cannot absorb a half-point rate move without the owner topping it up from salary.
Every deal has its own break-even Euribor, and it is a more useful number than the yield printed on the listing. Calculate it once, write it at the top of the file, and re-check it at every reset. Our break-even rent guide covers the mirror-image question: the minimum rent a property needs before it starts losing money.
Citation capsule: A 250,000 € Lisbon-metro rental at 80% LTV with a 1.00% spread breaks even at roughly 3.07% Euribor. With the 12-month rate at 2.993% in August 2026, that deal has an 8 basis point buffer — despite showing a 5.5% gross yield on the listing.
How do you defend a deal against rate moves?
There are only four real levers, and three of them have to be pulled before you sign. Once the deal is closed, the investor's optionality collapses to refinancing and rent reviews — both slow, both partly outside their control.
- Buy at a price that survives 4.5% Euribor. Not today's rate. Run the top scenario, and if the deal fails there, either the price comes down or you walk. This single test eliminates most marginal listings.
- Take less leverage than the maximum. The 80% ceiling is a limit, not a target. Dropping to 65% LTV on our example cuts debt service to about 9,310 € at today's rate and restores DSCR to 1.24. Lower leverage costs return in good scenarios and preserves ownership in bad ones.
- Price the fixed-rate premium against your buffer. If the deal only clears DSCR 1.20 at today's Euribor, the premium for a fixed or mixed-rate period is cheap insurance. If NOI covers debt service at 4.5% Euribor, paying for that certainty is a waste.
- Hold a reserve sized to the gap, not to a rule of thumb. If your break-even Euribor is 3.07% and a plausible stress case is 4.5%, the annual gap is about 2,180 €. Two years of that is your minimum reserve for this property.
The pattern we see repeatedly in listings screened against these assumptions: investors stress-test the rent and ignore the rate. They will model 10% vacancy without blinking, then assume the mortgage payment is a fixed input. It is the largest single line in the model and the only one indexed to something outside the property entirely.
Run the numbers on a specific deal with the Euribor cash flow calculator, then pressure-test the financing with the LTV stress test and the DSCR calculator.
Sources
- ativos.pt, Euribor (12-month rate, 2 October 2026), retrieved 2026-10-04, https://www.ativos.pt/euribor
- Banco de Portugal, Acompanhamento das medidas macroprudenciais em Portugal — Março 2026, retrieved 2026-08-27, https://www.bportugal.pt/publicacao/acompanhamento-das-medidas-macroprudenciais-em-portugal-marco-2026
- ComparaJa, Euribor Hoje: Taxas a 3, 6 e 12 meses atualizadas, 25 August 2026, retrieved 2026-08-27, https://www.comparaja.pt/credito-habitacao/euribor-hoje
- Millennium BCP, Banco de Portugal reforça regras do crédito habitação: taxa de esforço reduz para 45% a 01/08/2026, retrieved 2026-08-27, https://www.millenniumbcp.pt/afinal-contas/banco-portugal-reforca-regras-credito-habitacao
- Banco de Portugal, Taxas de juro no crédito à habitação — Portal do Cliente Bancário, retrieved 2026-08-27, https://clientebancario.bportugal.pt/en/interest-rates-home-loans
- Doutor Finanças, O que esperar das taxas de juro em 2026, retrieved 2026-08-27, https://www.doutorfinancas.pt/financas-pessoais/taxas-de-juro/o-que-esperar-das-taxas-de-juro-em-2026/
Frequently asked questions
What is the Euribor rate in 2026?
The 12-month Euribor stood at 2.993% on 25 August 2026, after stabilising through the year following the sharp 2022–2023 rise and the 2024–2025 reversal. The 12-month tenor indexes roughly 31.75% of existing Portuguese mortgage contracts, making it the most relevant benchmark for leveraged property investors.
How much can I borrow for an investment property in Portugal?
Banco de Portugal's macroprudential recommendation caps loan-to-value at 80% for any purpose other than own permanent housing, which includes buy-to-let. Own permanent housing can reach 90%. Investors should model a minimum 20% deposit plus acquisition taxes and costs on top of that.
What changed in Portuguese mortgage rules in August 2026?
From 1 August 2026, Banco de Portugal lowered the maximum debt service-to-income ratio from 50% to 45%, measured after an interest rate stress shock. Up to 10% of each institution's semi-annual lending may exceed the limit with documented justification. The change applies to solvency assessments made from that date.
At what Euribor level does a leveraged rental stop covering its debt?
In our worked example of a 250,000 € rental at 80% LTV with a 1.00% spread, pre-tax cash flow turns negative at roughly 3.07% Euribor. With the 12-month rate at 2.993% in August 2026, that deal sits about 8 basis points from break-even, despite looking healthy on a gross yield basis.
Should I choose a fixed or variable rate for a rental property?
It depends on the DSCR buffer, not on a rate forecast. If the deal only clears DSCR 1.20 at today's Euribor, a variable rate exposes you to negative cash flow on a single reset. A mixed or fixed period is worth the premium when the buffer is thin, and unnecessary when NOI covers debt service at 4.5% Euribor.