Disputing an energy bill in Belgium, up to the ombudsman

To dispute an energy bill in Belgium, you first write to the supplier, with evidence, then turn to the Energy Ombudsman Service if the answer is late or disappointing. It costs nothing. It often works: in 2023, seven closed cases out of ten ended with a positive outcome for the customer.

Is your gas bill really wrong?

Start here. Many complaints go nowhere because the bill was right and the consumption, for its part, had changed.

Droits Quotidiens says so at the top of its Walloon guide: a baby born during the year, a parent moving in, a second bathroom are enough to push a statement up. On a bill covering both gas and electricity, take each energy separately, with its own EAN code (the 18-digit identifier of each meter connection point), and go through these points:

• does the end-of-period meter reading say "estimated"? Compare it with the figure you read on the meter today;
• is the m³ to kWh conversion factor plausible, close to 11.6 kWh per m³, the reference value for the high-calorific gas now distributed everywhere in Belgium since the end of the conversion;
• does the billed period match your actual occupancy, with no overlap after a move;
• are all the advance payments you made deducted, at the right amount;
• is the unit price the one on your tariff sheet, fixed or variable, at the right date;
• is the printed EAN code really your meter's, and not your neighbour's.

The first two points explain most absurd gas bills. An estimated reading two years in a row can leave a catch-up of several hundred euros, as we showed in our article on meter reading, and a wrong factor distorts every kWh billed, as detailed in our guide to converting m³ to kWh.

How do you dispute an energy bill with the supplier?

In writing, with evidence. A phone call sometimes fixes a blatant error in five minutes, but it leaves no trace an ombudsman can use.

1. Photograph your meters, gas and electricity, with the date visible or today's newspaper.
2. Gather the disputed bill, the previous one, your contract or tariff sheet, and proof of your advance payments.
3. Write to the supplier: registered letter, email or the standard complaint form on its website. State your customer number, the invoice number, the EAN code or codes, the disputed amount and the correction you want.
4. Note the sending date and keep the acknowledgement of receipt or the case number.
5. Pay the undisputed part, so as not to add a payment dispute to the billing dispute.

You do not need one complaint per energy if you have a single contract. Just keep the two calculations apart in the letter.

What must the supplier do, and how fast?

In Wallonia, it has 10 working days at most to reply. Its answer must say whether the complaint is justified, unjustified, or needs further review.

The point that matters most comes next. If the complaint is found justified or in need of review, collection of the disputed amounts is suspended immediately, and the supplier can no longer ask you to pay them during the review. This rule mostly protects gas-heated households, whose winter settlement bill quickly exceeds a thousand euros. In Brussels and Flanders, the reply deadline is not published as clearly by the regional authorities: reread your supplier's general terms, which set its own.

When should you contact the Energy Ombudsman Service?

When the supplier has not replied within 20 days, or when its reply does not satisfy you. Not before.

The Energy Ombudsman Service is federal, independent and free. It handles complaints against gas and electricity suppliers and against distribution system operators (DSOs, the regulated companies that run the local grid and the meters, which you cannot choose): bills, advance payments, meter reading corrections, billing after a move, early termination fees, sales practices. You can reach it online, by email at plainte@mediateurenergie.be, by phone on 02/211.10.60 or by post at boulevard du Roi Albert II 8, box 6, 1000 Brussels.

The entry condition is strict, and the numbers show it: according to its 2023 activity report, the service received 23,047 complaints about a supplier and declared 49% of them inadmissible, first because the customer had not contacted the supplier or had done so insufficiently, then because 3,049 cases fell exclusively under regional powers and had to go elsewhere. So always attach your complaint and the reply you received.

One customer in two loses weeks over that formality alone.

Deadlines and costs, step by step

Table compiled on 20 October 2026. The 10-working-day deadline is the one Droits Quotidiens publishes for Wallonia.

Which body depends on your region?

The federal ombudsman handles the dispute with the supplier. Anything that falls to the DSO and to regional law, compensation, disconnections, connections, grants, follows another route, and that is where the 3,049 cases redirected in 2023 got lost.

In Wallonia, the regional SRME page, updated on 23 July 2026, covers among other things an error on a bill already paid and delays when switching supplier, with strict deadlines from the very first request. In Brussels, the 2025 report of Brugel's dispute service counts 302 complaints, 10% of them inadmissible, and 55% of admissible complaints found fully or partly justified. In Flanders, the Vlaanderen.be page sends billing disputes to the federal ombudsman and meter reading issues to Fluvius.

Pay or not pay during the dispute?

Pay what is not disputed. Always.

An unpaid amount triggers a reminder procedure, then fees: Test-Achats noted in April 2026 a cap of 20 euros on the flat-rate indemnity for a debt up to 150 euros, and interest at the legal rate of 4.5% after the reminder deadline. The disputed amount, for its part, is protected in Wallonia as soon as the supplier opens a review. If the bill is right but too heavy, ask for a payment plan rather than a dispute on principle, and consider lowering your advance payments for the following year.

102 euros on average per closed case

In 2023, the Energy Ombudsman Service closed 8,183 admissible cases, 72.6% of them with a positive outcome, amicable settlement or recommendation followed, and obtained 838,676 euros in compensation or redress, 102 euros on average. Billing accounts for 24.8% of complaints, meters for 23.1%, prices for 16.9%. The final recommendation does not bind the supplier; it has 30 days to justify a refusal.

The justice of the peace as a last resort

If mediation fails, the courts remain open, before the justice of the peace for most household bills. It costs fees and time, and the file built for the ombudsman, complaint, dated photos, supplier reply, becomes its backbone.

A correct bill, then a fair contract

A settled dispute is often the right moment to review your contract. Compare offers on total annual cost, gas and electricity included, in the energy supplier ranking, and go through each line of your statement with our guide to understanding your energy bill.

Sources. Droits Quotidiens, "Que faire si je ne suis pas d'accord avec mes factures de gaz et d'électricité ? (Wallonie)", updated 12 March 2026, and "Quel médiateur pour l'énergie ?", updated 20 February 2026. Federal Energy Ombudsman Service, press release on the 2023 activity report. Brugel, 2025 annual report of the dispute service, published 28 July 2026. Wallonie.be, procedure no. 4436 (SRME), updated 23 July 2026. Vlaanderen.be, "Klacht over energieleverancier, netbeheerder of Vlaamse Nutsregulator", accessed 20 October 2026. SocialEnergie, "Auprès du Service de Médiation pour le Consommateur", updated 7 May 2026. Test-Achats, fees on a late energy bill, 12 April 2026. Variable tariffs change every month: check the price on your tariff sheet at the date of the billed period.

Camille