What is a Deadlock Letter and when can I escalate my complaint?

The waiting period is 8 weeks. The Energy Ombudsman accepts a dispute where the complainant has received a deadlock letter or where at least 8 weeks have passed since the issue was first raised with the supplier without resolution³. The two routes sit side by side: the letter is faster, the 8-week clock is always available.

Once a deadlock letter is issued, a deadline starts. The dispute must be escalated within 12 months of receiving the letter³. That window is the single most important date in the process, and it runs from the letter, not from the original complaint.

What a deadlock letter is and when you get one

A letter of deadlock means your energy supplier has decided there is nothing else they can do about your complaint¹. Suppliers should send a letter called a decision letter or a letter of deadlock when they reach that point¹. The Energy Ombudsman uses the same two names, describing a final decision or deadlock letter as one of the triggers for registering a dispute².

The letter is not a rejection of the complaint in itself. It is a statement that the supplier's own process has finished, which is what makes external review possible. Ofgem's consumer guidance lists the circumstances in which escalation becomes available: a reported problem not fixed within 8 weeks, a failure to agree how to fix it, receipt of a deadlock letter, or dissatisfaction with the decision received⁸. A deadlock letter is therefore one of several doors into the same room, and it is the one the supplier controls.

Timing varies by supplier and by complaint. Some issue a letter once their final position is set; others let the 8-week clock run out without writing one at all. The Ombudsman's own description of the supplier's obligation is that they have 8 weeks to resolve your issue unless they send you a deadlock letter enabling you to come to us sooner⁹. That wording places the letter as an option available to the supplier, not a duty owed at a particular moment.

For a household, the letter matters because it converts an open-ended wait into a fixed deadline. It also fixes the supplier's final position in writing, which is the version of events the Ombudsman will review. Where a supplier has failed or is in administration, the letter may never arrive, and the 8-week route becomes the only one available.

The 8-week rule: two routes to escalation

The 8-week rule is the backbone of the complaints system. The Energy Ombudsman's eligibility wording is consistent across its supplier, network and heat network pages: it has been at least 8 weeks since the issue was first raised with the supplier, or a Deadlock Letter has been received⁴. Which of the two applies changes the timing, not the outcome.

The clock runs from first raising the issue, not from the most recent exchange. That distinction matters where a complaint has been reopened, passed between teams or answered with holding replies. The Ombudsman asks for sufficient evidence to support the case, including the date the complaint was raised¹⁰. A household that can show the original contact date is in a stronger position than one relying on a later reference number.

The two routes differ in one respect only: the deadlock letter can arrive before 8 weeks have passed, and when it does, escalation is available immediately. The Ombudsman states that suppliers have 8 weeks to resolve an issue unless they send a deadlock letter enabling the consumer to come to it sooner⁹. Independent reporting of the same rule puts it plainly: suppliers have eight weeks to respond to your complaint before you can escalate it, unless you receive a deadlock letter before this time period¹².

The timeframe itself is under review. The Energy Ombudsman has reported work on reducing the complaint escalation timeframe from the current eight weeks to six weeks⁷. Until any change takes effect, 8 weeks remains the figure that applies, and the deadlock letter remains the way to bypass it.

Eligibility to take your complaint to the Energy Ombudsman

Eligibility rests on three things: who you complained to first, how long has passed or whether a letter has been issued, and whether the evidence supports the case. The Ombudsman's guidance is explicit that a complaint must be raised with the supplier in the first instance, and that the service is free if the issue is not resolved after eight weeks or a deadlock letter is received⁶.

The standard checklist appears in near-identical form across the Ombudsman's dispute pages, whether the counterparty is a large supplier, a small one, a housing association or a heat network. The complainant must have complained to the supplier already, received a deadlock letter or waited 8 weeks without resolution, and hold sufficient evidence including the date the complaint was raised¹⁰. The supplier name must match the account holder's bill¹¹.

The scheme covers more than domestic suppliers. The Ombudsman runs separate arrangements for network operators and for heat networks, each with its own eligibility wording¹⁶. Heat network disputes follow the same 8-week or deadlock pattern, with the complaint raised against the heat supplier named on the bill¹⁸.

The escalation rule itself does not vary between England, Scotland, Wales and Northern Ireland. The 8-week and deadlock routes are stated in the same terms across the Ombudsman's guidance, and the older Ofgem leaflet describes the same eight-week threshold²⁰. What differs is the body a household complains to first, which depends on the supplier or network named on the account.

Where the routes fall short

The system has limits a household should know before relying on it. The first is that the Ombudsman reviews the supplier's conduct and the complaint, not the household's preferred outcome. The second is the 12-month deadline after a deadlock letter, which is easy to miss because it starts from the letter rather than the original problem³.

The third is evidence. The Ombudsman asks for sufficient evidence including the date the complaint was raised, and for the supplier name to match the account holder's bill¹⁰. A complaint made by phone without a reference, or by a third party whose name is not on the account, can fail on those grounds rather than on its merits.

The fourth is that a supplier in difficulty may not issue a letter at all. Where that happens, the 8-week route is the only one, and the household's own record of the complaint date becomes the load-bearing evidence. The Ombudsman's guidance does not require a letter where 8 weeks have passed⁴.

What to do with a deadlock letter, and what to do without one

A deadlock letter should be read for the supplier's final position, kept, and acted on inside the 12-month window³. The Ombudsman's case-creation guidance sets out what a dispute needs: the supplier allowed 8 weeks to resolve the dispute, or a deadlock letter allowing earlier escalation²¹. Where a letter exists, that condition is already met.

Without a letter, the household's task is to establish the 8-week point. The Ombudsman's wording is at least 8 weeks since first raising the issue with the supplier, or receipt of a Deadlock Letter⁴. Correspondence, reference numbers and the original contact date are what support that. The Ombudsman asks for sufficient evidence including the date the complaint was raised¹⁰.

The wider complaints route, from the supplier's own process through to the Ombudsman, is set out in how to complain about an energy supplier and escalate it, and the numbers for reaching a supplier or the Ombudsman are listed in who to call for an energy problem. What the Ombudsman can award once a dispute is accepted is covered in what resolution to expect from the Energy Ombudsman.

For a household's energy independence, the deadlock letter is a procedural lever rather than a supply one. It does not change who supplies the gas or electricity, or the price paid. What it does is remove the supplier's control over the timing of external review, converting an indefinite wait into a dated right of escalation. The dependence that remains is on the supplier to issue the letter, or on the household's own records to prove the 8 weeks have run.