What Is a Deadlock Letter in an Energy Complaint?
A deadlock letter can let you move to the Energy Ombudsman without waiting for the full supplier complaint period. But you need to know whether the message really closes the supplier’s position.
Use together
The short answer
A deadlock or final-position letter is the supplier saying it cannot do more to resolve your complaint. If you receive one, you may be able to escalate to the Energy Ombudsman before the normal waiting period has fully passed.
What the letter should help you prove
Complaint identity
The supplier should make clear which complaint it is responding to.
Final position
The response should explain the supplier’s final view or why it cannot resolve the issue.
Escalation route
It should tell you about the Ombudsman or next steps.
Date received
Save the date because timing matters when escalating.
Ask for final position wording
I raised this complaint on [date] about [one issue].
Please confirm whether this is your final response or whether you are still investigating.
If you cannot resolve the complaint, please provide your final position or deadlock letter so I can understand my escalation options.
Is what you received actually a deadlock letter?
Suppliers seldom use the word. What you are looking for is a response that closes their position and tells you where to go next — the regulatory term is a final response. Check it against these four markers.
| Marker | What to look for | Why it matters |
|---|---|---|
| Identifies the complaint | A reference number and a description of the issue. | A generic service email is not a final response to a specific complaint. |
| States a final position | “Our final response”, “we consider this closed”, “we are unable to do more”. | “We are still investigating” is the opposite of deadlock. |
| Mentions the Ombudsman | Almost every genuine final response signposts the Energy Ombudsman and the eight-week rule. | This is the strongest single indicator. |
| Is dated | A clear date on the letter or email. | Your twelve-month referral window runs from it. |
Three or four markers: treat it as deadlock and refer. One or two: ask the supplier to confirm, using the wording below. Do not guess — referring on a letter that is not a final response means the case bounces and you have lost weeks.
Asking for a deadlock letter, and when
You do not have to wait for one to be offered. Most suppliers will issue a final response on request once a complaint has genuinely stalled, and week four is a reasonable point to ask — early enough to save real time, late enough that they have had a fair chance.
Copy, fill in, send to the complaints address
Offering them option (a) matters. A request that reads as an ultimatum tends to get routed to a retention script; a request that gives them a way to keep the case open tends to get answered, and either answer is useful to you.
The twelve-month clock you must not miss
Once a deadlock or final response letter is dated, you have twelve months to refer the complaint to the Energy Ombudsman. After that, the case can be ruled out of scope no matter how strong the facts are.
The trap is obvious once stated and extremely common in practice: the letter arrives, you keep arguing with the supplier because it feels like progress, months pass, and the window closes while you are still in correspondence. Continuing to complain to the supplier does not pause the clock.
The moment a final response arrives
Save the full email or PDF. Put the date in your calendar. Set a reminder for ten months later titled “refer to Energy Ombudsman or lose the right”.
If the window has already closed
You are not necessarily finished. A new failure — a fresh incorrect bill, a new refusal, a broken promise — is a new complaint with its own clock. Raise it on its own facts rather than as a continuation of the old one.
The eight-week wait is being cut to six — but not yet
On 17 June 2026 the government published its response to the consultation Fairer, faster redress in the energy market. It confirmed three changes to this process:
| What changes | Now | Confirmed |
|---|---|---|
| Wait before you can escalate to the Ombudsman | 8 weeks | 6 weeks |
| Ombudsman's window to issue a decision | 6 weeks | 4 weeks |
| Penalties on suppliers who ignore a decision | None directly | Redress schemes gain the power to levy them |
Together that removes about four weeks from the consumer journey. Ofgem has also flagged the option of cutting the escalation wait further, to four weeks, in the longer term if the evidence supports it.
Be careful with the date. The response says the changes will happen “as soon as reasonably possible and certainly no later than Royal Assent for the Energy Independence Bill”. That means they are not in force as this page is written. Plan your complaint around eight weeks. If your case is still running in late 2026 or into 2027, check the current position before you assume you have to keep waiting — a supplier will not volunteer that the threshold has moved.
Source: DESNZ, Fairer, faster redress in the energy market: consultation response, published 17 June 2026.
Frequently asked questions
Is every complaint reply a deadlock letter?
No. A normal update or explanation is not necessarily a deadlock or final-position letter.
Do I still need evidence if I have a deadlock letter?
Yes. The letter opens the route, but evidence proves the billing issue.
Should I wait 8 weeks if I already have deadlock?
A deadlock or final-position letter can allow earlier escalation, but check the wording and keep the full message.
Does a deadlock letter mean I have lost?
No. It means the supplier has stopped moving, which is exactly the condition the Ombudsman exists for. A deadlock letter is the key to the next door, not a verdict.
How long do I have to use it?
Twelve months from the date of the letter. Diary it the day it arrives, because arguing with the supplier in the meantime does not extend the deadline.
Can the supplier refuse to give me one?
It can decline to call the matter closed while it is still genuinely investigating. What it cannot do is stall indefinitely — at eight weeks from your original complaint you can refer the case whether or not a letter exists.
What if the letter does not mention the Ombudsman?
Ask the supplier directly to confirm whether it is their final response. Keep the reply: a written confirmation serves the same purpose as the letter itself.
Official sources used for this page
BillDecoded translates official process and billing information into practical checks. It is not affiliated with the Ombudsman, Ofgem, Citizens Advice, Which? or any supplier.