As a consequence of the measures adopted by Real Decreto-ley 7/2026, of March 20, relating to temporary modifications in the taxation of hydrocarbons and VAT, the calculation of the variation in the price of fuel must be carried out using the average price of diesel before taxes (PAI), in order to correctly reflect the real evolution of the energy cost.
The formula applicable for calculating this revision is found in section 3.4 of the Annex to Order FOM/1882/2012, of August 1. In it, the variable G represents the index of variation of the average diesel price published by the Administration between the time of contracting and the time of execution of the transport.
As it is only a simulation, we do not assume any responsibility for the use made of this information, which is merely an estimate and approximate.
Average retail prices for diesel fuel at the pump, as published by the Ministerio para la Transición Ecológica y el Reto Demográfico, are provided on the website of the Ministerio de Transportes y Movilidad Sostenible.
In road freight transport, when the price of fuel varies by 5% or more between the date of the contract and the actual transport, the price initially agreed will be increased or reduced according to the criteria and formulas established by the Administration in the general contracting conditions.
Reference:
https://www.boe.es/eli/es/rdl/2026/03/20/7
Published in «BOE» no. 71, of March 21, 2026
Reference: BOE-A-2026-6544