Cost of owning a home in Cascais: IMI, AIMI and running costs (2026)

The main tax on owning a home in Cascais is IMI, charged at 0.35% of the property's tax value (VPT) for tax year 2025, collected in 2026. An own permanent home gets a 15% municipal reduction, which brings the effective rate to about 0.30%, and families can deduct a further €30 to €140. Owners with large holdings also pay AIMI, a national surcharge that starts at 0.7% above €600,000 of tax value per person.

On top of the taxes come the condominium, insurance and utilities. The sections below give each cost with its source, followed by yearly budgets for three example homes.

What is the IMI rate in Cascais?

For tax year 2025, collected in 2026, Cascais applies 0.35% to urban property. The rate was approved by the Assembleia Municipal on 22 December 2025 and published in Edital n.º 19/2026. It is a rise from 0.33% the year before, and it sits in the lower half of the national range of 0.3–0.45%.

The same edital sets reductions and surcharges. The own-home reduction comes from a separate municipal decision (Proposta 1802/2025) under the Cascais regulation on tax benefits.

The €300,000 VPT is an example value, not a typical Cascais figure. The rate for tax year 2026, collected in 2027, had not been set as of September 2026. The previous package was approved by the Câmara on 15 December 2025 and by the Assembleia Municipal a week later, so a decision is likely towards the end of the year; we will update this page when the new edital is published.

What is the VPT, and why does it matter?

IMI is charged on the Valor Patrimonial Tributário, the tax value the tax authority assigns to each property, not on what you paid. You find it on the caderneta predial, the property's tax record. Two flats with the same price can have different VPTs depending on age, location coefficients and when the value was last assessed.

Ask for the caderneta predial before you sign a promissory contract. With the VPT and the rates above you can calculate the IMI in one line, and it also tells you whether AIMI might apply.

How does IMI familiar work?

If the home is your own permanent residence and your household has dependants, Cascais deducts a fixed amount from the IMI bill: €30 with one dependant, €70 with two and €140 with three or more (Edital n.º 19/2026). The deduction comes after the 15% own-home reduction.

When is IMI paid?

IMI is charged to whoever owns the property on 31 December of the tax year and billed the following spring. If you buy in 2026, your first bill is for tax year 2026 and arrives in 2027; the seller pays the 2025 IMI collected in 2026. The number of instalments depends on the amount (PwC Guia Fiscal 2026):

• €100 or less: one payment in May.
• More than €100 and up to €500: two payments, May and November.
• More than €500: three payments, May, August and November.

Non-residents receive the bill through the Portal das Finanças, so keep your access and your electronic notifications active. The sister site explains how the NIF and fiscal representative work for owners who live abroad.

Can an own home be exempt from IMI?

Yes, but only at low tax values. Under art. 46 of the Estatuto dos Benefícios Fiscais, an own permanent home is exempt from IMI for three years if all of these apply:

• the VPT is €125,000 or less;
• the household's gross income in the previous year was €153,300 or less;
• you move in as your permanent home within six months of the purchase or completion.

The Assembleia Municipal can extend the exemption by two years, and a taxpayer or household can benefit only twice. After a purchase it is granted automatically; in other cases it must be requested within 60 days after the six-month period. Given Cascais price levels, check the VPT before counting on it.

Who pays AIMI, and how much?

AIMI (Adicional ao IMI) is a national tax on large residential holdings. It applies when the combined VPT of your homes and building land in Portugal exceeds €600,000 per person, or €1.2 million for married couples or civil partners who opt for joint taxation. Commercial, industrial and service property is outside AIMI.

Worked example: a villa in Cascais with a VPT of €1,000,000, owned by one person with no other Portuguese property, has a taxable value of €1,000,000 − €600,000 = €400,000, so AIMI is €400,000 × 0.7% = €2,800 a year. If the same villa belongs to a married couple who opt for joint taxation, the €1.2 million deduction covers the whole VPT and no AIMI is due. AIMI is assessed in June and paid in September (PwC Guia Fiscal 2026).

What do water and sanitation cost?

Water and sewerage in Cascais are supplied by Águas de Cascais. Its 2026 domestic tariff (before IVA) combines monthly availability charges with a price per cubic metre that rises with consumption.

By our arithmetic, a household using 10 m³ a month pays about €25.80 a month before IVA, and 20 m³ comes to about €49.35. A garden or pool pushes consumption into the upper bands quickly. The municipal waste tariff is billed separately and is not included here. Electricity, gas and telecoms depend on the contract you choose.

What do condominium fees look like?

There is no reliable published average for condominium fees in Cascais, so we do not quote one. Fees are set each year by the owners' assembly, split by each unit's share of the building (permilagem), and they vary widely: a small building on the Marginal with no lift costs far less than a gated development with gardens, a pool and a concierge.

Before you buy, ask for the approved budget for the current year, the minutes of the last two or three assemblies and the state of the common reserve fund that every condominium must keep. Minutes show approved works, which usually mean extra contributions. Since 2022 the seller must also present a statement from the building administrator listing the unit's condominium charges and any debts at the deed (Civil Code, art. 1424-A).

Is insurance compulsory?

In a building divided into units (propriedade horizontal), fire insurance is compulsory for each unit and for the common parts (Civil Code, art. 1429). Most owners cover this with a multi-risk home policy, which also includes water damage, storms and third-party liability; a bank lending on the property will normally require buildings cover. For a detached villa insurance is not compulsory, but it is the obvious precaution. If you let short-term, civil-liability cover of at least €75,000 is a condition of the AL registration, as set out in our short-term rental guide.

What does a year cost? Three example homes

The table uses assumed VPTs and water use to show how the costs combine. Condominium fees and insurance premiums vary too much to estimate, so they are listed as items to budget, not figures.

For the first home, IMI is €200,000 × 0.35% = €700, less 15% = €595, less €70 of IMI familiar = €525. If the holiday flat were let on a residential lease instead, its IMI would fall to €980 (0.28%). Rental income is taxed separately: from 2026 to 2029, residential rents of up to €2,300 a month are taxed at 10% under Decreto-Lei 97/2026, instead of the standard 25% flat rate on rental income.

To see what the purchase itself costs, read our guide to the cost of buying property in Cascais.

General information based on the rates and rules published as of 28 September 2026, not legal or tax advice. VPTs and water use in the examples are assumptions; ask a Portuguese tax adviser to check your own situation.