Break-even rent is the monthly rent a property needs to cover mortgage payments, vacancy, and operating costs. In Portugal, this matters because Global Property Guide estimates net yields are typically 1.5 to 2 percentage points below gross yields after costs.

Key takeaway: If realistic market rent is only slightly above break-even rent, the deal has no margin. One repair or empty month can erase the year's cash flow.

What is break-even rent?

Break-even rent is the point where monthly cash flow equals zero. It is not your target rent. It is your danger line. A good investment should sit comfortably above it.

Break-even rent formula

Break-even rent = (Mortgage + monthly costs) / (1 − vacancy rate) Monthly costs include condominium, IMI monthly equivalent, insurance, maintenance, and management if used.

Portugal worked example

Monthly inputValue
Mortgage payment€820
Condominium€55
IMI monthly equivalent€32
Insurance€18
Maintenance reserve€70
Total before vacancy€995
Vacancy assumption7%
€995 / (1 − 0.07) = €1,070 The property needs roughly €1,070 monthly rent just to break even before income tax.

This number also tells you when the problem is price, not rent. If the local market only supports €1,100 and the property breaks even at €1,070, the deal is too tight unless you can renegotiate the purchase price.

How much safety margin should investors require?

0–5%No marginAvoid or renegotiate
5–10%ThinOnly for very liquid areas
10–20%HealthyCan absorb normal surprises
> 20%StrongValidate the rent estimate

Run it now: use the break-even rent calculator to turn debt, vacancy, and costs into a single negotiation number.

Sources

  • Global Property Guide, Portugal Rental Yields, retrieved 2026-06-19, https://www.globalpropertyguide.com/europe/portugal/rental-yields