ISV explained: 6 common questions
The Vehicle Tax (ISV) is, for anyone who has never imported a car before, the biggest unknown in the whole process. It's also, by far, the line item that generates the most confusion and the most myths — from "imported cars don't pay ISV" (false) to "ISV is always half the price of the car" (also false, and highly dependent on the specific model). We've gathered the six questions we get asked most about this tax — without inventing figures, because the tables change every year and the only reliable place for an exact number is always the simulator with up-to-date data.
1. What exactly is ISV?
It's a tax that applies to motor vehicles the moment they're put into circulation in Portugal — whether because they're new, or because they're used vehicles coming from another country. For anyone buying a new car in Portugal, ISV is already baked into the price charged by the dealer. For anyone importing a used vehicle from another EU member state, it's the importer themselves (or, in our case, PuraRota on their behalf) who handles payment to the Tax Authority.
2. How is it calculated?
The calculation rests on two main components: one tied to engine displacement (the more cm³, the larger the component) and another tied to CO2 emissions (the more emissions, the larger the component). A percentage reduction is then applied to both, based on the vehicle's age since first registration — the older the car, the larger the reduction, though it never brings the tax down to zero purely because of age.
3. Why does the simulator ask whether the car is homologated under WLTP or NEDC?
These are two different CO2 emission measurement protocols, used during different periods of car production — WLTP is the newer and stricter one. ISV tables have different values depending on the protocol, because the CO2 figures each one produces aren't directly comparable. Using the wrong table can significantly change the final figure.
4. Do 100% electric cars pay ISV?
Currently, fully electric vehicles benefit from a full ISV exemption — both on the displacement component (which doesn't even apply, since there's no combustion engine) and on the environmental component. It's one of the biggest tax incentives driving electrification of Portugal's car fleet.
5. What about plug-in hybrids (PHEVs)?
Plug-in hybrids don't get a full exemption like electric vehicles, but they can benefit from a significant reduction on the displacement component when they meet two criteria at once: a minimum electric-only range and a maximum CO2 emissions limit. Outside those criteria, a PHEV is taxed like a conventional vehicle.
6. Where do I confirm the exact figure for my case?
In our simulator. By entering the engine displacement, CO2 emissions, homologation protocol and first registration date of the vehicle you're considering, the calculation engine automatically applies the tables currently in force and returns the estimated ISV — always broken down, never as a "magic" unexplained number.
Bonus: is ISV the same thing as IUC?
No, and it's a very common mix-up. ISV is paid once, at the moment the vehicle is put into circulation in Portugal (first registered here). IUC (the annual circulation tax) is a yearly charge, paid every year after that, directly to the Tax Authority — and it never forms part of the figure we calculate as total import cost, precisely because it's a recurring expense, not a one-off entry cost.
A note on precision
ISV values can be revised by the State Budget or standalone legislation at any point in the year. So any estimate — including our simulator's — should always be confirmed before a final purchase decision, ideally with the support of a licensed customs broker.
Why it's worth understanding this before you start looking for a car
It's tempting to start the search with your dream model and only think about ISV afterwards. In practice, reversing that order saves time and disappointment: understanding, even in general terms, how the displacement and CO2 emissions of the model you have in mind tend to weigh on the tax helps filter candidates before you invest time negotiating with sellers. A large-displacement SUV and an efficient city car start from very different points on the table — and that gap only grows once the environmental component is added.
How much ISV would you pay for your car?
The simulator automatically applies the current displacement, CO2 and age-reduction tables in force — no guesswork, no fine print.
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