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How is your car’s IUC calculated in Portugal?

IUC is Portugal’s annual car tax. For Category B you add engine size and CO₂, multiply by the year, and add a surcharge for diesel.

4 min readReviewed By Thorben Rasmus IdelReviewed by Nahar Geva

TL;DR

IUC is Portugal’s annual vehicle tax, owed by whoever owns the car on 1 January. For Category B (light passenger cars registered from July 2007), you add a component for engine displacement and one for CO₂ emissions, multiply by the registration-year coefficient (1.00 to 1.15), and add a surcharge for diesel cars. 100%-electric cars are exempt.

What is IUC?

The Imposto Único de Circulação (IUC) is Portugal’s annual tax on vehicles, what used to be called the "car stamp"1. It is owed every year by whoever owns the vehicle on 1 January, and is paid in the month of the registration anniversary. Don’t confuse it with ISV (the vehicle tax), which is paid once, when the car is first registered.

The amount depends on the vehicle’s category. This article (and our IUC calculator) focuses on Category B, the category of light passenger cars first registered from 1 July 2007, the vast majority of cars on the road.

What is Category B of IUC?

Category B covers light passenger and mixed-use cars whose first registration (in Portugal, the EU or the EEA) took place from 1 July 20071. Cars registered before that date belong to Category A and are taxed differently (by displacement and year only), and there are categories C to G for goods vehicles, motorcycles, boats and aircraft. This site’s calculator covers Category B.

How is IUC calculated (Category B)?

For Category B, IUC comes from two components added together and then multiplied by a coefficient, with a surcharge for diesel13:

IUC = (displacement component + CO₂ component [+ CO₂ surcharge if registered ≥ 2017]) × year coefficient + diesel surcharge

  • The displacement component is a fixed amount per engine-size band (cm³).
  • The CO₂ component is a fixed amount per emissions band (g/km).
  • The CO₂ surcharge applies to cars first registered from 2017 and only to the two highest CO₂ bands (+€31.77 and +€63.74). It is part of the CO₂ component, so it is added before the coefficient (and is multiplied by it too)1.
  • The year coefficient rises with the age of the registration (see below).
  • The diesel surcharge applies only to diesel cars, depends on displacement and is added last, after the coefficient.

Both the displacement and the CO₂ emissions are on your car’s registration document. You can estimate it all, component by component, in the IUC calculator.

How does the year coefficient work?

The coefficient is an age uplift: newer cars pay more. It is applied to the sum of the two components1:

  • 2007 → 1.00
  • 2008 → 1.05
  • 2009 → 1.10
  • 2010 onward → 1.15

So a car registered in 2010 or later always pays the maximum coefficient of 1.15.

What is the difference between WLTP and NEDC?

The CO₂ component is read from two different tables, depending on the homologation standard of the emissions3:

  • NEDC: used for older cars.
  • WLTP: used for cars homologated from around 2018.

The g/km bands differ (WLTP is stricter, with higher limits), but the euro amounts for each band are the same. Check your registration document for the applicable standard, using the wrong table can put you in the wrong band.

Worked example

Take a petrol car of 1,600 cm³, with 130 g/km of CO₂ (WLTP), registered in 2018:

  • Displacement component (1,251–1,750 cm³ band): €63.74.
  • CO₂ component (≤ 140 g/km on WLTP): €65.15.
  • Sum: 63.74 + 65.15 = €128.89.
  • × coefficient 1.15 (registered from 2010): €148.22.

As it is petrol, there is no surcharge. If it were the same car as a diesel, with 210 g/km (WLTP) and registered in 2015, the CO₂ component would rise to €212.04 and there would be a diesel surcharge of €10.07 (1,251–1,750 cm³ band), lifting the IUC to about €327.22. An identical car registered in 2018 or later would, being in the 206–260 g/km (WLTP) band, also pay a CO₂ surcharge of €31.77 added to the component before the coefficient. Test your case in the IUC calculator.

Do electric cars pay IUC?

100%-electric Category B cars are exempt from IUC1. Hybrids, even plug-in ones, are not exempt: they pay normally, based on their displacement and emissions, like any other car in the category. It is one of the most common misunderstandings.

When and how is IUC paid?

IUC is due every year, in the month of the vehicle’s registration anniversary, and can be paid on the Portal das Finanças (with a payment reference) or at a tax office2. It is owed by whoever owns the car on 1 January, so when buying or selling a used car, it is worth confirming who is responsible for that year’s tax.

IUC is the annual car tax; the annual home tax is IMI, see how IMI is calculated and estimate it in the IMI calculator. You may also want to see how investments are taxed: read what capital gains are and the related capital gains calculator.

Common mistakes

  • Confusing IUC with ISV

    ISV (the vehicle tax) is paid once, when the car is registered. IUC is the annual circulation tax, paid every year for as long as you own the vehicle.

  • Assuming hybrids are exempt

    Only 100%-electric Category B cars are exempt from IUC. Hybrids (even plug-in) pay normally, based on displacement and emissions.

  • Using the wrong CO₂ table

    The g/km bands differ between NEDC and WLTP. Using the wrong standard can change the band and the amount. Check your car’s registration document for its homologation standard.

Frequently asked questions

How is IUC calculated?
For Category B, you add the engine-displacement component and the CO₂-emissions component, multiply by the registration-year coefficient (between 1.00 and 1.15) and, for diesel cars, add a surcharge based on displacement.
What is Category B of IUC?
It is the category of light passenger and mixed-use cars first registered (in Portugal, the EU or the EEA) from 1 July 2007. It covers the vast majority of cars on the road.
Do electric cars pay IUC?
100%-electric Category B cars are exempt from IUC. Hybrids are not exempt: they pay based on displacement and emissions, like any other car.
What is the difference between the WLTP and NEDC tables?
They are two methods of measuring CO₂ emissions. Older cars use NEDC and cars homologated from around 2018 use WLTP. The g/km bands differ, but the euro amounts for each band are the same.
When is IUC paid?
Every year, in the month of the vehicle’s registration anniversary. It is owed by whoever owns the car on 1 January and can be paid on the Portal das Finanças.

Related reading & calculators

Sources

  1. 1.Vehicle Circulation Tax Code (CIUC), Article 10 (Category B) — Autoridade Tributária e Aduaneira / Portal das Finanças · retrieved 31 May 2026
  2. 2.Vehicle Circulation Tax (IUC), general information — Autoridade Tributária e Aduaneira / Portal das Finanças · retrieved 31 May 2026
  3. 3.IUC 2026 tables, amounts by engine-size and CO₂ band — DECO PROteste · retrieved 31 May 2026

Author / Reviewed by

Author

Thorben Rasmus Idel

Founder & writer

Co-founder of Calculadora Capital. Writes the methodology and verifies the math behind every page.

Reviewed by

Nahar Geva

Co-founder & reviewer

Co-founder of Calculadora Capital. Reviews the methodology and verifies the math behind every page.

Published: Updated: Reviewed:

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