Firms that receive 500 or more complaints in a six month period will have to publish the following information twice a year:
* How many complaints they have opened and closed;
* The percentage closed within eight weeks; and
* The percentage of complaints upheld.
Firms will need to present this information by five product areas: banking, home finance, general insurance and pure protection, life and pensions, and investments.
The FSA will then use this information to publish a consolidated list of complaints data covering all affected firms twice a year.
Sheila Nicoll, the FSA's director of conduct policy, said: "We are committed to greater transparency where this will help consumers. For the first time, people will be able to see how many complaints particular firms receive and how they handle them. We believe that this will help improve how firms treat their customers and provide incentives for firms to deal more effectively with complaints when they are received. Our more intensive approach to supervision places a greater focus on assessing how firms deal with their customers - and how firms handle complaints is a key part of this."
All affected firms will have published their first figures by 31 August 2010. The FSA will then publish its first set of consolidated data in September 2010.