What evidence do I need for an energy Ombudsman complaint?

Once a dispute is registered, there is a window of up to 14 days to upload supporting evidence¹. Most disputes are resolved within six weeks of the Ombudsman receiving evidence from both parties³, and once a resolution is accepted the supplier is obliged to implement it within 28 days¹. The service is free to the consumer⁴, and the most common financial award is around £50, though the maximum runs to £10,000 for domestic energy disputes³.

What the Energy Ombudsman is and when you can escalate to it

The Energy Ombudsman reviews complaints that a supplier has not resolved to the consumer's satisfaction. Ofgem's guidance is direct on the route: once a complaint is escalated, the Ombudsman will ask for information and evidence, review evidence from both the consumer and the energy company, inform the consumer of its decision within six weeks, and give the energy company a set of actions to resolve the problem⁵. The same escalation route is repeated across Ofgem's consumer pages, including complaints about billing, about the way a supplier has handled a complaint, and about the installation of a prepayment meter without permission⁶.

The service sits alongside, not instead of, the supplier's own complaints process. A household must complain to the supplier first, and the Ombudsman's eligibility checks require the complainant to confirm the company name matches the name on the account holder's bill, alongside sufficient evidence and the date the complaint was raised⁸. That name check matters in practice: it catches cases where a complaint has been logged against the wrong legal entity, which is common where a brand trades under a different licensed company.

For households thinking about energy independence, the Ombudsman is a backstop, not a source of supply. It cannot switch a household to a cheaper tariff, cannot install generation, and cannot reduce reliance on the grid or on gas. What it can do is force a supplier to correct a bill, clear an unfair charge or fix a fault, which protects the money a household would otherwise spend on its own energy measures. The dependence it addresses is dependence on a supplier's conduct, not on the network itself. For the wider picture of how suppliers are regulated and how complaints fit into it, see complaining about an energy supplier and the Energy Ombudsman.

The 8-week rule and deadlock letters: the gate you must pass first

The gate is stated identically across the Ombudsman's dispute pages: the complainant must have received a deadlock letter, or it must have been eight weeks without the complaint being resolved². The two are alternatives, not a sequence. A deadlock letter is the supplier's formal statement that it cannot take the matter further, and it opens the Ombudsman route immediately. Without one, the eight-week clock runs from the date the complaint was first raised with the supplier¹².

The supplier's side of the same rule is set out for companies: they have eight weeks to resolve the issue unless they send a deadlock letter enabling the consumer to come to the Ombudsman sooner¹³. That framing is useful for a household because it establishes that the eight weeks is a maximum, not a target, and that a supplier can release the complaint early by issuing the letter.

The rule applies across company types. It covers the large suppliers, smaller licensed suppliers, housing associations and management companies that appear in the Ombudsman's dispute listings, and heat network operators¹⁴. It also survives a supplier failure: where a supplier has ceased trading and the customer has moved to a new supplier under the supplier of last resort process, a complaint to the new supplier that remains unresolved after eight weeks can still be pursued through the Energy Ombudsman¹⁸.

For feed-in tariff generators, a separate route exists: a domestic or micro business FIT generator whose complaint has not reached a mutually agreeable outcome after eight weeks can refer it to the Ombudsman²⁰. The related pages on how long before a complaint can go to the Ombudsman and what a deadlock letter is cover the timing in more detail.

Evidence you need: what to gather and the 14-day upload window

The evidence requirement is stated in the same terms on every dispute page: sufficient evidence to support the case, including the date the complaint was raised with the named supplier². In practice that means three things. First, a dated record of the original complaint, whether that is a sent email, a web form confirmation, a letter or a note of a call with the date and the adviser's name. Second, the correspondence that followed, including any holding responses and the final position. Third, the underlying documents: bills, statements, meter readings, photographs, and records of payments or direct debits.

The upload window is up to 14 days to upload evidence to support the case¹. That is a firm operational limit, and it is worth preparing the file set before registering the dispute rather than after. The Ombudsman accepts pdf, csv, txt, doc, docx, xls, xlsx, ppt, pptx, png, gif, jpg, bmp, mov, mp4, mp3, m4a, tif, tiff, msg, wav and eml files¹. That range covers documents, spreadsheets, presentations, images, video, audio and email files, so a photograph of a meter display, a recording of a call and an exported email thread can all be submitted.

A practical file set for a billing dispute typically includes:

• The dated record of the first complaint to the supplier
• The supplier's responses, including any deadlock letter
• Bills or statements covering the disputed period
• Meter readings or photographs taken at the relevant dates
• Bank or payment records showing what was actually paid
• Notes of phone calls, with dates, times and adviser names

The Ombudsman will also ask the supplier for its own evidence, and the decision is made on both parties' material⁵. Where a company disputes acceptance of a case purely on the basis that it believes it acted appropriately, followed policy, or that the remedy sought is unachievable, the Ombudsman will decline that case acceptance dispute²¹. That is a procedural point rather than an evidential one, but it explains why the consumer's own file needs to show what was asked for and what was refused.

What the Ombudsman can decide: awards up to £10,000 and possible outcomes

The Ombudsman's remedies are financial awards and required actions. The most common financial award is around £50, sometimes called a Time and Trouble Award¹. Awards are based on the cost of putting things right, such as ensuring the consumer has been charged accurately, clearing unfair charges or fixing faults³. The maximum varies by the type of company and the terms of reference covering that scheme³.

The gap between the average award of around £50 and the £10,000 maximum is the single most misunderstood part of the scheme. The maximum is a ceiling for the most serious cases, not an expectation. The Ombudsman also states plainly that the level of maximum financial award may vary depending on the type of energy company and the terms of reference that cover that scheme³, so a dispute against a network operator and a dispute against a broker do not carry identical limits.

The Ombudsman does not fine suppliers. It decides remedies and sets out the actions a company must take, and the company is obliged to implement an accepted resolution within 28 days¹. Fines and enforcement are a matter for Ofgem. The Ombudsman's own guidance for suppliers frames the relationship as one of resolving individual disputes rather than imposing penalties¹³.

Who can use the service: domestic, small business and microbusiness eligibility

The service covers both domestic and small business consumers in the energy sector²³. Only domestic consumers, micro-businesses and small businesses may apply²⁰. The small business test is set out in full: a company has fewer than 50 employees or their full-time equivalent, and has an annual turnover of at most £6.5 million or a balance sheet total of £5.0 million, or has an annual electricity consumption of not more than 200,000 kWh or an annual gas consumption of not more than 500,000 kWh²³.

A separate microbusiness threshold applies in some schemes: the business employs fewer than ten employees or their full-time equivalent and has an annual turnover or balance sheet no greater than the stated limit²⁴. The distinction matters because the maximum award differs between small business and micro business consumers in the flexibility services scheme³.

Heat network disputes have been within scope since 1 April 2025, covering consumers and small businesses²⁵. The same evidence and timing requirements apply, and the complainant must confirm the date the complaint was raised with the named heat supplier¹⁴. Ofgem's heat network guidance confirms that the party responsible for handling complaints is the Energy Ombudsman, but that consumers should first notify their heat supplier and try to resolve the issue²⁶. For more on this market, see heat network suppliers and households.

How long it takes and what happens after you accept a resolution

Most disputes are resolved within six weeks of the Ombudsman receiving evidence from both parties³. That figure sits inside the wider commitment to inform the consumer of the decision within six weeks of escalation⁵. The two are consistent: the six-week decision window runs from the point at which both sides' evidence is in hand, which is why the 14-day upload window matters so much to the overall timeline.

Once a resolution is accepted, the supplier is obliged to implement it within 28 days¹. That obligation is the practical value of the scheme: the outcome is not advisory. If the supplier fails to implement the remedy, the Ombudsman can be told, and the case can be reopened.

The sequence, in order, is:

1. Complain to the supplier and keep a dated record.
2. Wait eight weeks, or receive a deadlock letter.
3. Register the dispute with the Ombudsman by website, telephone, email or post²³.
4. Upload evidence within 14 days¹.
5. The Ombudsman reviews evidence from both parties and issues a decision, on average within six weeks of receiving it³.
6. Accept the resolution; the supplier must implement it within 28 days¹.

Registration channels are website, telephone, email or post, and the published enquiry address is enquiry@energyombudsman.org⁵. The Ombudsman's pages list two different telephone numbers, 0845 055 0760 and 0330 440 1624, and the two figures disagree, so the current number should be checked on the Ombudsman's own site before calling.

A case can be refused. The Ombudsman will refuse to accept a case where it is apparent that the consumer is pursuing a dispute without merit and intends to cause inconvenience, harassment or expense to the supplier, which it calls a vexatious complaint¹. It will also decline a case acceptance dispute made purely on the basis that the company believes it has taken appropriate corrective action, followed policy appropriately, that the remedy requested is unachievable, or that an element is outside the terms of reference when other issues are within them²¹.

For households, the independence question is straightforward. The Ombudsman resolves the dispute and compels the remedy, but it does not change who supplies the home, what tariff applies afterwards, or how exposed the household is to wholesale prices. It restores money that was wrongly taken and corrects a record; it does not reduce dependence on a supplier or on the grid. The related pages on complaining about an energy supplier and energy supplier customer service ratings set that backstop in context.