Portugal Scraps the Birth-Month Car-Tax Deadline, Shifting All Drivers to a Shared IUC Calendar From 2027

If you own a car in Portugal, the annual ritual of remembering to pay your IUC in the month your vehicle was first registered is on its way out. On 9 July the Conselho de Ministros (Council of Ministers) approved the change to the Código do IUC (the Vehicle Circulation Tax code) that untethers the tax from each car's registration month and moves every owner onto a common, calendar-based payment schedule. Crucially, this is a change to when you pay, not how much — the Government has stressed the reform "is limited to reorganising the payment dates and does not result in any increase in the tax."

The Imposto Único de Circulação (Single Circulation Tax, or IUC) is the yearly tax every vehicle owner pays simply for having a car, van or motorcycle registered in Portugal. Until now it has fallen due in the vehicle's "birth month" — the month of its first registration — which meant tens of different personal deadlines scattered across the year and, the Government says, a lot of people forgetting.

Why the change

Ministers point to the scale of accidental non-payment under the old system: since 2020, the tax has generated 5.6 million penalty proceedings (contraordenações) and 1.8 million tax-enforcement cases (execuções fiscais), largely because owners lost track of an idiosyncratic deadline. The Secretary of State's office, under Finance Minister António Leitão Amaro, argues that a single, predictable calendar — much like the one already used for the IMI property tax — will cut that "uncertainty and unpredictability" and reduce the number of drivers accidentally slipping into default.

How the new calendar works

Once the reform is fully in place, IUC will be organised around a common annual window anchored on April, with the number of instalments depending on the size of the bill:

• Up to €100: a single payment, due by the end of April.
• More than €100 and up to €500: two instalments — April and October.
• More than €500: three instalments — April, July and October.

Anyone who prefers to settle the whole amount at once can still pay it in full in April, regardless of the sum. Miss an instalment, though, and the remaining ones become due immediately.

Mind the transition year

The switch does not happen in one step, and this is the part worth pinning down. 2026 is unchanged — this year's IUC still falls due in your vehicle's registration month. 2027 is a transition year with its own temporary calendar: bills up to €500 are paid in a single instalment in October 2027 (with the option to pay in full in July), while bills above €500 are split across July and October 2027. The permanent, April-anchored model then takes over from 2028. The staggered rollout is deliberate — it avoids drivers having to pay two years' worth of IUC within a few months of each other.

What is — and isn't — changing

It is worth repeating, because it is the point most easily misread: the calculation of the tax is untouched. The brackets based on engine capacity (cilindrada) and CO₂ emissions, the diesel adicional, and the exemptions for electric vehicles and disability all stay exactly as they are — our guide to how the IUC is calculated still applies. What changes is only the timetable. The reform also lands after a turbulent year for the tax, in which the Constitutional Court restored former owners' right to prove they had sold a vehicle before being billed for it.

What This Means for You

• This year: nothing changes. Pay your 2026 IUC in your car's usual registration month as before.
• From 2027: the deadline moves. Watch for the October 2027 transition date rather than your old birth-month; from 2028, budget for April (and July/October if your bill is larger).
• Your bill won't rise because of this: the reform reorganises dates only — the amount you owe is set by the same engine-size and emissions rules as before.
• If you own a higher-taxed car: you may find the payment automatically split into two or three instalments, though you can still choose to pay it all in April.

For a tax that most drivers experience as a once-a-year scramble to remember an oddly personal deadline, a shared national calendar is a modest but genuinely useful simplification — provided everyone notes that the familiar April rhythm only fully arrives in 2028, with an unusual October date to navigate first.