The FOS says data will include the numbers of new cases and the percentage of closed cases where there has been a change of outcome in favour of the consumer.
Data will be broken down into five groups including banking, home finance, general insurance and pure protection, decumulation, life and pensions and investments.
The FOS says it will identify any larger groups that businesses belong to, as well as major trading names used.
The Ombudsman rebuffed industry arguments that this could result in businesses paying unjustified complaints to avoid a referral and that publication of the data could undermine consumer confidence in the financial services sector.
It states: “Financial businesses will be encouraged to deal with complaints properly in the first place. And if they are confident that they have treated the complaint fairly, they will stand by their decision. There will be no reason to pay-off unjustified complaints, because these will be shown up by the percentage of cases upheld.
“We are not persuaded by the argument that publication of business-specific complaint data will undermine consumer confidence in financial services. If it were undermined by the number of complaints and the percentage upheld, the damage has already been done – because aggregate complaint data is already published.”
The first set of data is due to be published for the six months to September 2009.
Which? personal finance campaigner Vera Cottrell says: “Forewarned is forearmed, so publishing details of complaints could help consumers to make more informed choices about the financial firms they deal with.
“However, we think these proposals could go much further. For example, having a threshold of 30 complaints before a firm is named means that smaller companies could continue to get away with murder and no one would know.”