I’ve been googling and can find nothing that contradicts this information that I found on an international investment advisers website:
“*You can continue to own Premium Bonds when you move to France, but as soon as you become resident here they stop being tax free, and all your winnings are subject to tax. *
Many British expatriates also have Individual Savings Accounts (ISAs) and Personal Equity Plans (PEPs). The income derived from them is tax free for UK residents, but again, they are not tax efficient investments for French residents. The income from both cash ISAs and share ISAs and PEPs are fully taxable here in France.
*Investment income is now taxed as general income in France at rates of to 45%. You then pay another 15.5% in social charges. *
If you have a big Premium Bond win, you could lose up to 60.5% of the winnings to tax!
You are obliged to declare the earnings on your annual French tax return. The local tax authorities are likely to find out about it anyway, considering the high level of exchange of information between European countries these days.”
If this information were out-of-date I would have thought they would have updated it. If the winnings from premium bonds became tax free I suspect there would be more advisers talking about it. The reason they are taxed is that unlike games of chance here in France where you can lose the lot, your initial investment in a premium bond is always safe.