New rates applying on 12 October

Portaria No 451-A/2026/1, published on 9 October, sets the mainland Portugal ISP rate for unleaded petrol falling within CN codes 2710 12 41 to 2710 12 49 at EUR 419.48 per 1,000 litres. The amount includes the road-service allocation of EUR 87 per 1,000 litres. The instrument expressly enters into force on 12 October 2026. [PT_451]

For diesel falling within CN codes 2710 19 42 to 2710 19 48 and 2710 20 11 to 2710 20 19, the new rate is EUR 265.13 per 1,000 litres. It includes the road-service allocation of EUR 111 per 1,000 litres. These amounts are unit tax rates; they are not an announcement of retail selling prices. [PT_451]

An adjustment from the previous week

The previous instrument, Portaria No 448-A/2026/1, had set the petrol rate at EUR 428.15 and the diesel rate at EUR 264.40 per 1,000 litres from 5 October. The exact comparison therefore shows a EUR 8.67 per 1,000 litre decrease for petrol, equivalent to 0.867 euro cent per litre, and a EUR 0.73 increase for diesel, equivalent to 0.073 euro cent per litre. [PT_451] [PT_448]

That comparison measures only the change in the statutory ISP rate between the two instruments. It does not measure the total tax change per litre, reconstruct VAT or establish the price actually paid. Rounding, contracts, stocks, costs and commercial decisions may produce a different result on an invoice or at the pump. [PT_451] [PT_448]

The temporary mechanism described in the instrument

The preamble states that the adjustment forms part of a temporary and extraordinary mechanism. Where the price increase exceeds 10 cents relative to the reference week of 2 to 6 March, the Government intends to return additional VAT revenue by temporarily reducing the ISP rate. For the week beginning 12 October, the condition is stated to be met for both fuels. [PT_451]

For that week, the reductions resulting from the mechanism are quantified at EUR 96.47 per 1,000 litres for diesel and EUR 78.04 for petrol. These figures explain how the rate was calibrated, but are not credits that each purchaser may claim individually. The instrument adjusts the upstream ISP tariff; it does not create a general direct refund procedure for consumers. [PT_451]

The territorial and product scope remains narrow

The Portaria applies to the mainland. It cannot establish the same amounts for the autonomous regions without a review of their own rules. Its material scope is also defined by Combined Nomenclature codes. A commercial label such as petrol or diesel is insufficient if the product does not fall within one of the codes expressly listed. [PT_451]

The effective date separates two closely spaced periods: the Portaria 448-A tariff applies from 5 October, and the Portaria 451-A tariff from 12 October. For movements occurring at the boundary, a business must apply the excise tax-point rules and document the event used. Invoice date alone may not resolve the issue. [PT_451] [PT_448]

Operational updates for fuel businesses

Warehouse keepers, importers and distributors should check CN-code and rate configurations from 12 October. The change file should retain both Portarias, the deployment date, test results and the list of affected products. A configuration error should be separated from commercial price changes so that any tax effect can be calculated independently. [PT_451] [PT_448]

Invoice controls can reconcile taxable volume, the 1,000-litre unit, product code and period. They should also distinguish the total ISP rate from the road-service allocation included within it. Adding EUR 87 or EUR 111 again would double count the allocation, because the Portaria states that those amounts are already incorporated in the rate. [PT_451]

No automatic change in the final price

The preamble anticipates a decline in the diesel price and an increase in the petrol price for the week concerned, then adjusts the ISP reduction accordingly. This is the Government’s forward-looking explanation, not a guarantee for every observed price. The ISP changes in the opposite direction to that forecast: a small rise for diesel and a larger reduction for petrol. [PT_451] [PT_448]

Internal or customer communications should therefore separate three figures: the expected market movement, the ISP-rate movement and the price actually invoiced. Combining them would create a promise that the legal instrument does not contain. The operative provisions neither set commercial margins nor impose a single amount of pump-price change. [PT_451]

Scope and limitations

This analysis is based on the complete official texts of Portarias 451-A/2026/1 and 448-A/2026/1 reviewed on 12 October 2026. It compares their rates and effective dates without reconstructing any particular excise chain or analysing the rules specific to the Azores or Madeira. It reaches no conclusion on a refund or invoice correction for any identified business. [PT_451] [PT_448]

Targeted research on the new measure did not identify a directly relevant judicial decision. That result does not establish the absence of case law on ISP, customs codes or tax points. Any retrospective correction must therefore be based on the transaction facts and the rule applying at the relevant date, rather than on the arithmetic comparison of the two Portarias alone. [PT_451] [PT_448]