What is a deadlock letter and how do I get one?

Short answer

A deadlock letter is a company’s written confirmation that its complaints process is exhausted — the trigger that lets you go to an ombudsman without waiting the usual 8 weeks. You cannot declare deadlock yourself, but you can ask for one in writing at any point.

A deadlock letter — the term energy and telecoms firms use — is the same thing as a final response letter in financial services: a written statement that the company's internal complaints process is exhausted and it will not go further. It is not a defeat. It is the key that unlocks an independent ombudsman months earlier than the usual waiting period would.

How to recognise one, and how to ask for one

Not every letter from a complaints team is a final response. Look for wording such as:

“This is our final response to your complaint.”
“We are unable to take this matter any further.”
“We have now completed our investigation.”
“If you remain dissatisfied, you may refer this matter to …” — followed by the name of an ombudsman or ADR scheme.

Regulated firms, particularly energy suppliers and financial businesses, must tell you which scheme covers your complaint and how to reach it. If that is missing, ask. You can also ask for the letter itself: put in writing, “Please either resolve my complaint or issue a deadlock/final response letter confirming your final position.” A company cannot be forced to send one, and you cannot declare deadlock on its behalf — but if it refuses and the sector's waiting period has passed, the ombudsman will take your case anyway, and the refusal is worth reporting to the regulator.

The clock the letter starts

The letter opens a window, and the window closes:

Financial services: refer to the Financial Ombudsman Service within 6 months of the final response — the letter must state this deadline.
Energy and telecoms: 12 months from the deadlock letter.
Legal services: 1 year from the firm's final response.
Property agents: 12 months from the agent's final response.

Diarise the date the day the letter arrives. Then read it properly — a partial offer inside a final response may still be worth taking — note the deadline, and build your pack: the original complaint, every reply, the deadlock letter, and a one-page dated chronology, which is the single most useful document an investigator can receive. Ombudsmen can accept late referrals for good reason such as serious illness or bereavement, but that discretion is never guaranteed.

Read the full guide: What Is a Deadlock LetterCovers eligibility, the process, deadlines, and next steps in depth.

Related guides

What Is a Deadlock Letter

A deadlock letter — sometimes called a final response letter — is a formal written notice from a company stating that it has reached the end of its internal complaints process and cannot offer any further resolution. Receiving one is important: it is your trigger to escalate the complaint to an ombudsman without waiting the usual 8 weeks.

7 min read

When and How to Escalate a Complaint

If a company has failed to resolve your complaint satisfactorily, or if it has gone beyond the response deadline, you have the right to escalate. Escalation means taking your complaint to an independent body — such as an ombudsman, regulator, or the courts — who can investigate and enforce a resolution.

5 min read

Complaint Response Timelines in the UK

Different organisations and sectors have different deadlines for responding to complaints. Knowing the applicable timelines helps you understand when a response is overdue, when you can escalate, and when you are at risk of losing your right to take your complaint to an ombudsman.

5 min read

Financial Ombudsman Service: How to Complain

The Financial Ombudsman Service (FOS) is the UK's free, independent dispute resolution service for complaints about financial products and services. It handles over 200,000 complaints a year covering everything from bank charges and payment protection insurance to insurance claim rejections and mortgage disputes.

9 min read