Yes, all interest on all cash ISAs is tax free, no matter how long they've been held. But as the interest being paid on most cash ISAs is very low at the moment, you should check regularly to see whether you can get a better deal by transferring it to another provider. If you want to do this, DON'T withdraw the money or close the account yourself as this will cause it to lose its tax-free status. You need to write to your provider and fill in a transfer form. They will then handle the transfer to your new provider without you being involved.