Your bank sends you a letter. It's polite, it's final, and it says no. No refund for the fraud, no reversal of the fee, no acknowledgment that anything went wrong. Most people read that letter as the end of the road. It isn't. It's the point where a completely free, government-backed arbitrator is allowed to take over your case — and the bank can no longer simply decide it doesn't want to pay.
What the Financial Ombudsman Service actually is
The Financial Ombudsman Service (FOS) is the UK's official, independent dispute resolution service for financial complaints. It doesn't work for the bank and it doesn't work for you — it's set up under the Financial Services and Markets Act 2000 to investigate disputes between consumers and financial firms (banks, insurers, lenders, payment providers) and decide who's right based on the evidence. Using it costs nothing.
Its decisions carry real weight. If the Ombudsman rules in your favour and you accept the decision, it becomes binding on the firm — they have to pay. You, on the other hand, are never forced to accept an FOS decision you disagree with; you keep the right to pursue the matter through the courts instead. As of the current 2026/27 financial year, the FOS can order a firm to pay compensation of up to £455,000 for complaints about conduct that occurred on or after 1 April 2019 (the limit is lower, currently £205,000, for older conduct) — and this limit rises annually in line with inflation.
The 8-week rule, explained properly
You can't go straight to the Ombudsman. UK-regulated firms are required under the FCA's DISP rules to be given a chance to resolve a complaint directly first. Here's the actual timeline:
- Week 4: if the firm hasn't resolved your complaint yet, it must send you a written update telling you it's still being looked at.
- Week 8: the firm must either send you a "final response" — its formal decision — or explain in writing why it can't yet and when it expects to.
- After week 8: if you've had no final response, you can go straight to the FOS without waiting any longer. You don't need the firm's permission.
- If you get a final response you disagree with (at any point, even before week 8), you have 6 months from the date of that letter to refer the case to the FOS. Miss that window and you generally lose the right to use the service for free.
When this actually applies
The FOS handles a wide range of disputes, but three patterns come up constantly:
Fraud denied without real evidence. You reported an unauthorised transaction in time, and the bank replied with a generic letter claiming its "investigation" found the payment was authorised — without showing you what that investigation actually consisted of.
Fees you never agreed to. Overdraft charges, account fees, or penalty charges that weren't clearly disclosed in your terms, or that were applied because of an error the bank itself made.
Bad information sent to credit reference agencies. An account you closed is still showing as open, or a dispute you won is still being reported as an unpaid default to Experian, Equifax, or TransUnion.
How to build a case the Ombudsman can actually act on
An FOS investigator works from what you submit, so vague frustration doesn't get you far — a clear paper trail does. Before you refer your case:
- Keep the firm's final response letter (or its written explanation for why it hasn't issued one)
- Gather your account statements covering the disputed period
- Write out a plain timeline: when the issue happened, when you complained, every date you heard back
- Be specific about what "fair" looks like to you — a refund, a fee reversal, a correction to your credit file
- Everything is submitted online through the FOS's own case form; you don't need a solicitor or a claims management company to use it
Why firms often settle before the Ombudsman rules
Financial firms pay the FOS a case fee for complaints that reach a formal investigation, regardless of who wins. That cost, combined with the risk of a public uphold record with the regulator, is often enough to make a firm offer to settle once it sees a well-documented complaint has actually been referred — rather than let an ombudsman rule against them formally.