Key figures — as of 2026-08-28: 22.5% of Lisbon's housing stock — roughly 71,990 units — sits outside the permanent housing market, combining vacant homes with short-let (AL) registrations — vacancy by parish ranges from 9.4% in Lumiar to 37.1% in Santa Maria Maior — nationally, 12% of Portugal's dwellings stood vacant at the 2021 census, one of the highest shares in the OECD — an updated valuation base could push aggravated IMI on an empty Lisbon home to as much as €11,900 a year.
A Fifth of the City, Locked Away
Lisbon's own residents have put a number on a problem officials have been reluctant to quantify. Adding the 24,512 existing AL registrations, the universe of homes outside the permanent housing market rises to around 71,990 units — 22.5% of the city's total housing stock. The residents' association Vizinhos em Lisboa, which compiled the figures, put it bluntly: the city debates the need to build more housing while more than a fifth of its stock stays out of the market.
The distribution is wildly uneven. Vacancy in the capital doesn't stop at the historic centre — it ranges from 37.1% in Santa Maria Maior to 9.4% in Lumiar, with Arroios showing the highest absolute number of empty dwellings, at 3,424. In Areeiro, a middle-class residential parish with little tourist pressure, the vacancy rate reached 15.7% — 1,830 empty homes, of which 730 (42%) were empty for "other reasons" unrelated to being for sale or rent. That detail matters for foreign tenants: it suggests a chunk of Lisbon's empty stock isn't sitting on the market waiting for a buyer or tenant at all — it's simply withheld.
The association's proposed fix is a full, map-based inventory of the municipal housing stock, arguing that the current lack of data around vacant properties helps explain informal or illegal occupation of empty buildings.
Why the Official Numbers Don't Add Up
The gap between what the state records and what residents estimate is the real story here. Portugal's municipalities have consistently under-tracked vacant housing: in 2023 municipalities had identified 12,803 vacant dwellings, while census data from 2021 suggest a substantially larger number. At national level, Portugal has one of the largest housing stocks relative to population in the OECD, and the share of dwellings not used as primary residences — either vacant (12% in 2021) or holiday homes (19%) — is the highest in the OECD.
Strip the 24,512 AL units out of Lisbon's 71,990 off-market figure and roughly 47,478 units are genuinely vacant, closer to the municipality's own historic estimates for the city. Set against the state's national tally of 12,803 officially registered empty homes, that's GrowIN's own back-of-envelope read: Lisbon's unofficial vacant stock alone would be nearly 3.7 times larger than the government's entire nationwide count of registered empty dwellings. If that arithmetic holds, the official register isn't just incomplete — it's missing most of the picture in the one city where the housing crunch bites hardest for foreign renters and buyers.
The Tax Lever Portugal Already Has
Portugal doesn't lack tools to push empty homes back into use — it under-uses the ones it has. Updating the tax base for aggravated IMI to reflect current values would significantly increase the financial cost of keeping dwellings vacant — aligning property values with 2024 market prices could more than double aggravated taxes, to up to €11,900 annually for an average-sized dwelling in Lisbon. Yet the current minimum rate — 0.9% in Lisbon — may not be dissuasive enough to change owner behaviour. Enforcement remains weak too, which is precisely the gap the residents' registry proposal is aimed at closing.
What It Means for Foreign Renters
The same central parishes flagged for the highest vacancy — Santa Maria Maior, Misericórdia, Santo António — are also the ones under the tightest short-let restrictions. Lisbon's 2025 local-accommodation regulation set absolute containment (new registrations banned) where the AL-to-housing ratio hits 10% or more, and Santa Maria Maior, Misericórdia and Santo António remain in absolute containment. That means the city is simultaneously squeezing tourist-let supply and sitting on tens of thousands of empty long-term homes in the exact same neighbourhoods expats and digital nomads most want to live in. A working registry, paired with a credible IMI penalty, is the missing link between the two policies — and could, in theory, do more to loosen Lisbon's rental market than another round of construction incentives. As GrowIN Portugal Editorial puts it: a city can't fix what it refuses to count.
For anyone renting or relocating to Lisbon, this is a story to watch rather than a policy already in force — check our relocation guide before signing a lease in a contention-zone parish, and see tax & NIF for how IMI and the AIMI surcharge already apply to property owners, including non-residents holding empty flats. Nothing here changes today's rules, but a public vacant-homes registry, if the Câmara adopts one, would be the first real transparency tool this market has had in years.