The pump price is four prices stacked together
Every price you see on a European forecourt is built from the same four layers: the cost of the refined product itself, which tracks international markets and is broadly similar across the continent; the distributor's and the station's margin; national excise duty; and VAT applied on top of everything — tax on tax.
The first two layers do not vary that much between neighbouring countries. The last two vary a great deal, and that is almost the whole story of why crossing a border changes the price.
Why the fuel itself costs roughly the same everywhere
Refined product in north-west Europe is traded in a single regional market, moved by pipeline, barge and coastal tanker between a small number of large hubs. A litre of diesel destined for Belgium and a litre destined for the Netherlands may well have come off the same ship. Transport adds a few cents over distance, and landlocked or peripheral regions pay a little more, but the underlying commodity cost does not jump at a frontier.
This matters because it tells you where not to look for the explanation. When the same fuel costs meaningfully more twenty kilometres further on, the fuel is not what changed.
Excise duty: the EU sets only the floor
EU law — the Energy Taxation Directive, 2003/96/EC — sets minimum excise rates: €0.359 per litre for unleaded petrol and €0.330 per litre for diesel. Every member state is free to tax above that floor, and most do, some by a wide margin. That single decision, taken country by country and revisited in each national budget, creates most of the gap you see at the border.
Excise is also a fixed amount per litre, not a percentage. That has a consequence drivers notice: when the underlying oil price falls, the tax component does not fall with it, so pump prices drop by less than the headline crude move would suggest. It works the other way too — a high-tax country's prices are proportionally less volatile.
VAT multiplies the difference
VAT is charged on the fuel plus the excise duty, and standard VAT rates across the EU range roughly from 17% to 27% depending on the country. A higher excise duty therefore gets amplified by a higher VAT rate, which is why the spread between the cheapest and the most expensive EU countries is wider than the excise tables alone would suggest.
The arithmetic is worth seeing once, with illustrative round numbers rather than real ones. Take a product-plus-margin cost of 70 cents a litre. Add 50 cents of excise and 21% VAT and you get about 145 cents. Add 70 cents of excise and 25% VAT to the same 70-cent base and you get about 175 cents. The fuel was identical. The 30-cent difference is entirely the two governments.
Reduced rates, rebates and other national exceptions
Several member states operate reduced excise rates for commercial diesel, refundable to hauliers rather than shown at the pump — so the price on the sign is not the price a truck ultimately pays. Some regions apply territorial reductions, and during recent price spikes a number of governments introduced temporary rebates or caps that expired at different dates in different countries.
The practical consequence for a driver is that comparisons more than a few months old can be wrong in ways that look like data errors but are actually policy changes. A price map is only as current as its last update, which is why every number on Refuelia carries the day it was recorded.
Where the official numbers live
The European Commission publishes the Weekly Oil Bulletin — consumer prices of petroleum products, with and without taxes, for every member state, updated weekly. Because it gives both figures, you can separate the two questions that usually get muddled: is fuel expensive here, and is fuel taxed heavily here. They are not the same question and they do not always have the same answer.
It is the reference dataset for comparing countries honestly, and one of the sources Refuelia links to on country pages where official data exists. Our guide on where fuel prices come from lists the national feeds country by country, including which ones are mandatory and which are voluntary.
What this means for your tank
If your route crosses a border, it is worth checking both countries' current levels before deciding where to fill up — and worth knowing that stations in border regions often price differently from the national average precisely because they compete across the line. A station five kilometres inside the cheaper country may be dearer than one twenty kilometres in.
Refuelia shows stations on both sides of any border on the live map, and country pages show which official price source covers each market. Where we have no recent data for a station, we say so. We never estimate a price and present it as a reading.