With another IMI payment approaching in November, homeowners in Portugal are being encouraged to check whether they could be paying more than necessary.
DECO PROteste has warned that some properties may have tax valuations that no longer reflect factors used to calculate the annual bill. That could mean an owner continues paying a higher amount even when a fresh assessment might produce a lower valuation.
As RTP reports, it's the property's valour patrimonial tributário (usually abbreviated to VPT) that's in issue. That's the value for tax purposes rather than the price you paid for the property or the amount you might sell it for.
Some elements in the calculation, including those relating to the building’s age, are not automatically adjusted in a way that guarantees the lowest possible bill. DECO’s advice is to check the figures through a simulation.
However, requesting a new valuation should not be an automatic next step.
A reassessment can also increase the VPT, leaving the owner with more tax to pay. DECO PROteste therefore recommends using its free simulator, available through its Impostos Simples platform, before deciding whether to submit a request.
There is another reason to take care: a reassessment on the grounds that the valuation is outdated is generally subject to a three-year interval. The Tax Authority confirms this rule in its guidance, which also states that this type of request is not subject to a fee.
One thing that makes the calculation so pertinent this year is the detail in DECO's guidance that the base value per sq m used in property valuations has increased from €665 to €712.50 for 2026. That new figure can be used when a property is revalued, which could in effect negate the reduction that would be due to the age of the property. An older house in itself doesn't necessarily equate to a cheaper bill.
For owners whose simulation does show a saving, the end of the year matters. DECO says a favourable reassessment requested by 31 December could reduce the IMI payable in 2027. It would not reduce the instalment due this November.
The amount involved depends on both the valuation and the municipality’s tax rate. The Tax Authority explains that the standard rate for urban properties generally ranges from 0.3% to 0.45%.
As a simple illustration, a property with a VPT of €150,000, taxed at 0.3%, produces an annual bill of €450 before any applicable deductions or exemptions. If its VPT fell to €130,000 and the rate stayed unchanged, the bill would become €390—a saving of €60 a year.
Meanwhile, existing payment deadlines still apply. Bills above €100 and up to €500 are normally split between May and November. Those above €500 are divided into three payments, in May, August and November.
Checking the valuation could be worthwhile, particularly for anyone who has not looked at it for years. The useful first step is a simulation, followed by a decision based on the result.