How to Complain to the Financial Ombudsman Service (and Get Results)
Most people complain to their bank or insurer, get a final refusal, and give up. They shouldn't.
There is a free, independent body — the Financial Ombudsman Service (FOS) — set up specifically to resolve disputes between consumers and financial firms in the UK. It has the power to award compensation, overturn decisions, and compel firms to act. Its decisions are binding on firms. It costs nothing to use.
Most people who reach a dead end with a financial firm do not know it exists. Many who do know about it assume the process is complicated, slow, or stacked in the firm's favour. None of that is true. This guide explains how the FOS works, who can use it, and what turns a complaint into a result.
What is the Financial Ombudsman Service?
The Financial Ombudsman Service is an independent statutory body established under the Financial Services and Markets Act 2000. It adjudicates disputes between individual consumers (and qualifying small businesses) and firms authorised by the Financial Conduct Authority (FCA). It is not a regulator — it does not fine firms or set industry-wide rules — but its decisions carry legal force and are binding on the firms involved.
The FOS covers complaints about:
- Banks and building societies
- Insurance companies (home, car, travel, health, income protection)
- Credit cards and store cards
- Personal loans and hire purchase agreements
- Mortgages and equity release products
- Pension providers and annuity providers
- Investment firms and financial advisers
- Debt collection firms and payday lenders
The service is entirely free to consumers. The firm pays a case fee regardless of outcome — there is no cost to bringing a complaint, even if the FOS finds in the firm's favour.
The 8-week rule: your trigger for escalation
Before the FOS will accept your complaint, you must have complained to the firm directly and given them a reasonable opportunity to respond. Under FCA rules, firms have 8 weeks to send a Final Response to a complaint.
Two things entitle you to go to the FOS:
You have received a Final Response Letter
Also known as a deadlock letter. The firm has stated its final position and you disagree with it. This letter should explicitly notify you of your right to refer the matter to the FOS.
8 weeks have passed without a substantive response
If the firm has not replied at all, or has only sent an acknowledgement, the 8-week clock is your mandate to escalate — regardless of their internal timelines.
Keep your original complaint and any acknowledgement you received. These establish the date the 8-week clock started.
Financial Ombudsman time limits — do not delay
Once you receive a Final Response Letter, you have 6 months to refer your complaint to the FOS. Miss that window and the FOS will ordinarily decline to investigate.
For complaints about events that occurred before 9 July 2015 (the date rule changes came into effect), different time limits may apply — typically you must complain within 6 years of the event, or 3 years from when you became (or ought to have become) aware of it. If your dispute involves older conduct — such as legacy PPI mis-selling or historic charges — check with the FOS directly.
The key point is this: if you are near the 6-month mark, act now. The FOS has discretion to accept late complaints in exceptional circumstances, but it exercises that discretion narrowly. A complaint submitted one day after the deadline may be refused.
The date of your Final Response Letter is the date on the letter — not the date you opened it or replied to it. If you are unsure when the clock started, contact the FOS directly before submitting.
Who can use the Financial Ombudsman Service?
The FOS is primarily designed for individual consumers. It also accepts complaints from small businesses, charities, and trusts that meet specific size criteria: broadly, organisations with fewer than 10 employees and annual turnover or balance sheet below €2 million.
To bring a complaint, the firm you are complaining about must be authorised by the FCA. You can check this at the FCA Register at register.fca.org.uk.
The FOS handles disputes involving:
- Bank charges and account closures
- Insurance claim rejections or underpayments
- Mis-sold financial products (PPI, packaged bank accounts, payment protection)
- Payment disputes and unauthorised transactions
- Credit and loan issues, including irresponsible lending
- Mortgage payment disputes and arrears handling
- Pension transfers and advice complaints
The FOS will not investigate complaints about the general level of a firm's charges (as opposed to how charges were applied), or disputes that are already before a court.
How to complain to the Financial Ombudsman Service: step by step
Complain to the firm first
This is mandatory. The Financial Ombudsman Service will not accept your complaint unless you have already raised it with the firm directly. Write to them formally — keep a copy of everything you send and receive.
Wait for the firm's Final Response (up to 8 weeks)
The firm has 8 weeks to respond. Their reply will either resolve the complaint or come in the form of a Final Response Letter — sometimes called a deadlock letter — explaining their position and informing you of your right to go to the FOS. If 8 weeks pass without a substantive response, that alone entitles you to escalate.
Gather your evidence
Pull together your correspondence with the firm (emails, letters, live-chat transcripts), the original policy documents or contract, account statements showing the disputed transactions or charges, and any notes you made at the time. You do not need a thick file — but targeted, specific evidence outweighs volume every time.
Submit your complaint to the FOS
File online at financial-ombudsman.org.uk or by post to Exchange Tower, London E14 9SR. Attach your Final Response Letter (or a note confirming 8 weeks have elapsed), a clear summary of your complaint, the outcome you want, and the key evidence. The service is entirely free to consumers.
An investigator reviews your case
An FOS investigator will contact both you and the firm. Most cases are resolved at investigator level within three months. The investigator will reach a view and, if they find in your favour, invite the firm to settle. Most firms do — an ombudsman escalation costs them more in time and reputational risk than compliance.
Accept or escalate to a formal ombudsman decision
If the firm rejects the investigator's view, the case goes to a formal ombudsman. Their decision is final and binding on the firm — provided you accept it. You are not bound: you can reject an ombudsman decision and pursue other routes, including court. Most consumers accept because the outcome is the same as a court award, with none of the cost or complexity.
What a strong FOS complaint letter looks like
The FOS weighs evidence. An investigator reviewing your case will look at what the firm did, what the relevant rules required, and whether the firm's conduct fell short. A generic “I'm unhappy with how my claim was handled” email gives them almost nothing to work with.
A complaint letter that gets results does three things:
Cites the specific rule breached
Not just “FCA rules” — the precise provision. For insurance complaints: FCA Handbook rule ICOBS 8.1.1 (requirement to handle claims promptly and fairly). For credit complaints: CONC 7 (treatment of customers in financial difficulty). For investment advice: COBS 9 (suitability of advice). Naming the rule forces the firm to engage with it directly.
Quotes the firm's own policy wording back at them
Insurance rejections often rely on policy exclusions. A letter that quotes the clause the insurer is relying on, and then explains why it does not apply to your circumstances, is far harder to dismiss than a letter that simply objects in general terms.
States the remedy sought clearly and specifically
The FOS can award compensation for financial loss, distress, and inconvenience. A letter that quantifies the loss — “the rejected claim amount of £3,400, plus £200 in consequential costs, plus interest at 8% per annum” — anchors the investigation. Vague letters produce vague outcomes.
This is precisely what Fight My Corner letters are built to do: cite the applicable FCA rule, quote the firm's own policy back at them, and state the remedy with legal precision.
Common disputes the FOS handles
The FOS receives over 150,000 complaints per year. The most common categories include:
Insurance claim rejections
Storm damage, flood, health conditions, pre-existing condition exclusions
Bank account closures
Accounts closed without adequate notice or explanation
PPI mis-selling
Legacy complaints still within applicable time limits
Overdraft charges
Unarranged overdraft fees, charges applied during financial difficulty
Mortgage payment disputes
Arrears handling, charges, forbearance failures
Section 75 credit card disputes
Firm refusing to accept joint liability under the Consumer Credit Act 1974
If the firm is FCA-authorised and you have complained directly first, the FOS will almost certainly have jurisdiction. When in doubt, submit — the FOS will tell you if it cannot investigate.
Ready to write your FOS complaint letter?
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Write my letter — from £9.99 →Fight My Corner provides dispute letter generation tools and guidance — not legal advice. For complex financial disputes involving significant sums, consider seeking advice from a financial solicitor or your local Citizens Advice bureau.