A firm reference number (FRN) is the unique identifier the UK's Financial Conduct Authority assigns to every firm it authorises, and the key the Financial Services Register is searched by. It is the most reliable way to look a broker up, because a name, a trading name and a domain can all be copied, while the number resolves to exactly one entry — showing the legal entity, its permissions, its approved trading names, its registered address and the status and dates of its authorisation.
Other supervisors publish the same idea under different labels: CySEC issues licence numbers, ASIC issues AFS licence numbers, and most registers can be searched by number as well as by name. What matters is the direction the check runs in. Take the number from the client agreement or the firm's own regulatory footer, search the regulator's register for it, and confirm that the entry names the entity you are actually being asked to contract with. A reference number quoted at you that belongs to a different company on the register is the standard signature of a clone firm.
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What a Prop Firm Challenge Actually Tests
The profit target gets the marketing and the drawdown rule ends the attempt. What the evaluation is really measuring, which clauses decide the outcome, and how to read a firm's rules before you pay.