How is a car’s ISV calculated in Portugal?

What is ISV?

The Imposto Sobre Veículos (ISV) is the tax paid once, when a car is registered in Portugal, whether new or imported used¹. It is the heaviest tax on the price of an imported car and the first thing to estimate before buying.

Do not confuse ISV with IUC (Imposto Único de Circulação): ISV is paid once, at registration; IUC is the annual circulation tax. This article (and our ISV calculator) focuses on Table A, which covers light passenger cars (the vast majority of cars).

How is ISV calculated (Table A)?

For Table A, the ISV is the sum of two components¹³:

ISV = displacement component + environmental component (CO₂) [+ diesel surcharge]

Each component is computed the same way (value × bracket rate − deduction) and is never below zero:

• The displacement component uses the engine displacement (in cm³).
• The environmental component uses CO₂ emissions (in g/km, WLTP standard).

Displacement and emissions are on the car’s certificate of conformity and registration document. You can estimate everything, component by component, in the ISV calculator.

Displacement component (2026)

Environmental component: CO₂ (WLTP), petrol (2026)

Diesel has its own table, with higher values, and the brackets climb very steeply above certain emission levels, that is where the ISV jumps³. The full per-bracket values are in the calculator.

The diesel surcharge

Diesel cars whose particulate emissions reach 0.001 g/km (or whose data is missing) also pay a fixed 500 € surcharge added to the ISV³. Modern diesels with an efficient particulate filter may fall below that threshold and avoid the surcharge, so in the calculator this surcharge can be turned on or off.

Imported used cars: the age reduction

When importing a used car, the ISV is first computed as if it were new and then a reduction is applied based on time in use since first registration (Art. 11 of the CISV)²:

In other words, the older the car, the lower the ISV. A car over 10 years old pays only 20% of what it would pay new.

Plug-in hybrids and electric cars

• Plug-in hybrids that meet the legal requirements (minimum electric range and low CO₂ emissions) pay only 25% of the ISV, a 75% reduction³.
• 100%-electric cars are exempt from ISV (and from IUC)³.
• Other (non-plug-in) hybrids pay the full Table A ISV.

Worked example

Take a new petrol car of 1,500 cm³ and 130 g/km of CO₂ (WLTP):

• Displacement component: 1,500 × 5.61 − 6,194.88 = €2,220.12.
• Environmental component (121–130 g/km band): 130 × 5.27 − 619.17 = €65.93.
• ISV = 2,220.12 + 65.93 = €2,286.05.

The same car as a diesel with 120 g/km would pay €2,781.12 displacement + €369.01 CO₂ + €500 particulate surcharge = €3,650.13. And if that petrol car were imported used at over 5 years (a 52% reduction), it would come to 2,286.05 × 0.48 ≈ €1,097.30. Test your case in the ISV calculator.

Importing a car: the DAV and the deadlines

If you bring a car in from abroad you do not pay the ISV in the country you bought it in. You pay it here, when the vehicle is released for consumption so that it can receive Portuguese plates. The request is made with a customs vehicle declaration (declaração aduaneira de veículo, DAV), filed electronically on the tax authority's customs portal⁴.

The deadlines are set in the Code and they are short:

The DAV must be accompanied by the foreign registration certificate, the invoice or bill of sale, the certificate of conformity and the transport document where the car does not enter under its own power (article 20(2))².

And one rule sets the whole timetable, which almost no page highlights: article 27(3) forbids registering a taxable vehicle until customs has confirmed to the IMT that the ISV is paid, guaranteed or exempt². In other words: no settled ISV, no plates, which is why the tax paces the entire process. Thirty days past the due date without payment, the Code even provides for seizure of the vehicle.

Time in use is counted up to the DAV deadline

The age reduction does not depend on when you get round to the paperwork. Article 11(2) defines "time in use" as the period between the first foreign registration and the end of the deadline for filing the DAV². The law, not your schedule, fixes the age band.

The same article also has an escape route worth knowing: under paragraph 3, the taxpayer may ask the customs director, up to the end of the payment deadline, to assess the tax under an alternative formula based on the vehicle's market value, where that produces less than the table. The ISV calculator follows the table, which is the route applied by default.

What else it costs to register an imported car

The ISV is almost always the largest item, but it is not the only one. Separate from it are the roadworthiness test for plate assignment and the IMT registration, whose fees are set by those bodies and should be confirmed with them. We do not quote them here so as not to publish a figure that may no longer be in force. And if the car comes from outside the European Union, customs duties and import VAT are due as well: see the customs duties calculator.

When and how is ISV paid?

ISV is due when the vehicle is released for consumption, in practice, when it is registered in Portugal¹. It is paid once, unlike IUC. After registration, the car then pays the IUC every year: see how IUC is calculated and estimate it in the IUC calculator. Before buying an imported car, it is always worth estimating the ISV, often the biggest slice of the cost of legalising it in Portugal.