All insurers which allow named drivers to earn no claim bonus do not give the same NCB that main drivers/policy holders will get. You can a fraction of the real NCB and that depends from insurers to insurers. So full no claims discount is not given and the catch is that you need to stay with the same company which gave you no claims as the additional driver to take advantage of it. This means you can only get the discount when you take out a policy in your name with the same insurer, that is, you shift from being a named driver to the policyholder.
