Professional diesel in Spain: the direct aid falls in September, the total support holds

Anyone refuelling in Spain will notice a change on this month’s statement. The direct aid for professional diesel, which was due to rise to 20 cents a litre in September, has gone down. It is not a cut in support: it is a transfer from one mechanism to the other.

Royal Decree-Law 18/2026 of 29 June built fuel support out of two parts that always add up to 25 cents a litre — a cut in the hydrocarbons tax, applied directly at the pump, and a direct aid paid to hauliers registered for professional diesel.

The original design and what changed

The plan was to withdraw the tax discount step by step and make up for it with direct aid:

Month	Tax reduction	Direct aid	Total
July 2026	15 cents/l	10 cents/l	25 cents/l
August 2026	10 cents/l	15 cents/l	25 cents/l
September 2026 (planned)	5 cents/l	20 cents/l	25 cents/l

The decree, however, included a safeguard clause: if the July diesel price index exceeded that of the same month a year earlier by more than 15%, the tax reduction in September would rise to 20 cents a litre. Prices rose 15.7% in July. The clause was triggered.

The result, in September: 20 cents through the tax and about 5 cents of direct aid, keeping the total at 25 cents. The tax reduction is confirmed in the BOE text; the exact amount of direct aid left is what the Spanish trade press and Fenadismer have reported, and the AEAT will set it in the monthly calculation.

Why this really matters

For cash flow, it is not the same where the discount comes from.

• Through the tax, the discount appears immediately in the price paid at the pump. No claim, no wait, no money advanced.
• Through the direct aid, the haulier pays the full price and recovers it later, in the AEAT refund cycle.

In other words: in September more money stays in the pocket at the moment of refuelling, and less is left pending a refund. For anyone covering a lot of kilometres in Spain, that improves the month’s cash flow even though total support is unchanged.

Foreign hauliers are entitled too

This is the point most often missed. Professional diesel is not reserved for Spanish companies: vehicles registered in other EU Member States can sign up to the AEAT register of beneficiaries and claim the partial refund of the hydrocarbons tax on diesel consumed in Spain.

What registration requires for vehicles registered outside Spain:

• the vehicle’s registration number and country of registration;
• the date the vehicle started operating;
• the maximum authorised mass;
• the number of the administrative transport authorisation and the issuing body.

Registration must come before consumption. Diesel bought before registration cannot be recovered — an expensive and common mistake in companies that only discover the scheme after months on the Iberian run.

Refuelling must be paid for with a means of payment accepted for this purpose, linked to the registration number, so the consumption is allocated to the right vehicle.

A 30 October deadline for those left out

There is a second aid, distinct from this one, for land transport professionals who cannot be beneficiaries of the professional diesel refund — cases such as taxis, private hire vehicles, ambulances and certain urban services. It is not per litre: it is a fixed amount per vehicle, which the AEAT puts between €150 (taxi, private hire) and €1,350 (heavy lorry).

Two practical notes: it is incompatible with the professional diesel aid — they do not stack — and the claim is filed between 1 September and 30 October 2026. Anyone who qualifies and misses the deadline loses the whole amount.

In short

If you are registered for professional diesel, you need do nothing: the adjustment is automatic and total support stays at 25 cents. If you run the Iberian route and are not yet on the AEAT register, it is worth sorting out now — the benefit only counts from registration onwards. And if your case is the per-vehicle aid, the calendar closes on 30 October.

The measures in Royal Decree-Law 18/2026 run until 30 September 2026. What comes after has not been published yet, and it is not worth counting on before it is in the BOE.