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.

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.