UK Financial Ombudsman Service (FOS): Complete Guide to Filing an Insurance Complaint

The Financial Ombudsman Service (FOS) is the UK's free, independent dispute resolution service for financial services complaints — including all types of insurance. If your insurer has denied a claim unfairly, delayed resolution, or handled your complaint poorly, the FOS is your primary escalation route. Understanding how it works and how to use it effectively can be the difference between an overturned denial and an unresolved dispute.

What Is the Financial Ombudsman Service?

The FOS was established by the Financial Services and Markets Act 2000 and is funded by levies on regulated financial firms. It is completely free for individual consumers and small businesses. The FOS resolves disputes between consumers and FCA-regulated financial businesses, including:

• Private medical insurance (PMI)
• Life insurance
• Critical illness insurance
• Income protection insurance
• Travel insurance
• Home and contents insurance
• Pet insurance
• Car insurance

The FOS cannot help with products that are not regulated by the FCA, or with disputes about commercial policies taken out by large businesses.

Who Can Use the FOS?

You can use the FOS if you are:

• An individual (personal insurance policyholder)
• A small business with an annual turnover under £6.5 million and fewer than 50 employees
• A charity or trust with assets under £5 million

Most private insurance policyholders in the UK qualify.

Before You Can Go to the FOS: Exhausting Internal Complaints

You must first go through your insurer's internal complaints process before the FOS will accept your case. This means:

1. Filing a formal written complaint with your insurer
2. Allowing the insurer up to eight weeks to respond with a Final Response Letter
3. Either receiving an unsatisfactory Final Response, or having the eight weeks elapse without a final response

Once either of those conditions is met, you have six months from the date of the Final Response Letter to contact the FOS. Do not let this deadline pass — once it does, the FOS may not be able to help.

How to File a Complaint With the FOS

Online: The fastest route. Visit financial-ombudsman.org.uk and use the online complaint form. You will need:

• Your name and contact details
• The name of the insurer you are complaining about
• A description of your complaint and what outcome you want
• Copies of key documents: the denial letter, your Final Response Letter, policy documents, and any medical or supporting evidence

By phone: Call 0800 023 4567 (free from UK landlines and mobiles) Monday to Friday 8am–5pm, and on Saturdays 9am–1pm. Staff can take initial details and help you understand the process.

By post: You can also submit by post if you prefer. The address is: Financial Ombudsman Service, Exchange Tower, London, E14 9SR.

What the FOS Investigator Will Look At

Once your case is assigned to an investigator, they will:

1. Request the insurer's full case file — including its internal notes, any medical assessments it commissioned, and the reasoning behind its decision
2. Review your complaint, supporting evidence, and desired outcome
3. Assess whether the insurer's decision was fair and reasonable given the policy terms and applicable law and regulation
4. Consider whether relevant FCA rules (including Consumer Duty) were followed
5. Form a provisional view and share it with both parties

In most cases, the investigator's provisional view leads to a resolution — either the insurer agrees to change its position, or the customer accepts the outcome.

Timelines: What to Expect

• Initial acknowledgement: usually within a few days
• Investigator assigned: typically within a few weeks, though backlogs vary
• Preliminary view issued: this varies widely — from a few weeks to several months for complex cases
• If the provisional view is contested, the case is referred to an Ombudsman for a final decision, which can add several more months

If your case involves an urgent health or financial risk, tell the FOS when you contact them. Urgent cases can be prioritised.

What the FOS Can Order an Insurer to Do

If the FOS upholds your complaint, it can direct the insurer to:

• Pay the denied claim in full
• Pay backdated amounts from when the claim should have been honoured
• Pay interest on the outstanding amount
• Compensate you for financial losses caused by the delay or denial
• Pay a distress and inconvenience award (typically £100–£750 for significant cases, more in exceptional circumstances)
• The maximum award the FOS can make is currently £430,000

If the FOS dismisses your complaint, the insurer is not required to change its decision. You retain the right to pursue legal action, though this is rarely practical for smaller disputes.

Building the Strongest Possible FOS Case

Be specific. Vague complaints are harder to assess. Identify exactly what was denied, when, and why the insurer's reasoning is wrong.

Include the right documents. The most important documents are: the denial letter, the Final Response Letter, your policy document and IPID, and any medical or clinical evidence supporting your claim. Do not submit unnecessary documents — clarity helps your case.

Cite FCA Consumer Duty. The Consumer Duty (effective July 2023) requires insurers to deliver fair outcomes for retail customers. If the insurer's denial produces a clearly unfair outcome, say so explicitly and explain why.

Address the insurer's reasoning directly. Do not just repeat your original claim — respond specifically to the reasons the insurer gave for denial. Show why those reasons are incorrect or misapply the policy.

Get medical evidence if the claim involves health. The FOS takes medical evidence seriously. A consultant or GP letter that directly addresses the insurer's specific objections is far more powerful than a general statement of illness.

Common Mistakes to Avoid

• Missing the six-month deadline after the Final Response Letter
• Contacting the FOS without first completing the insurer's internal complaints process
• Failing to include the Final Response Letter in your submission (the FOS cannot open your case without it)
• Being vague about what outcome you want — be specific (e.g., "I want the insurer to pay £4,500 for the denied surgical procedure")
• Submitting incomplete medical documentation

The FOS and the FCA Consumer Duty

Since July 2023, the FCA's Consumer Duty requires all regulated insurers to ensure their products deliver real value and their claims processes produce fair, consistent outcomes. The FOS now regularly considers Consumer Duty compliance in its assessments. This is a powerful additional lever — if an insurer's denial contradicts the reasonable expectations created by its policy documentation, the Consumer Duty argument may tip the balance in your favour.

Fight Back With ClaimBack

Whether you are preparing to file with the FOS or building your internal complaint before escalation, ClaimBack helps you organise your case, identify the strongest arguments, and present your evidence in the format most likely to succeed.

Start your appeal at ClaimBack

Related Reading

• UK Health Insurance Claim Denied: FOS, FCA, and Your Full Appeal Rights
• How to Write an Insurance Appeal Letter
• Internal vs. External Insurance Appeals