I don’t know if this has been mentioned before, but I just remembered it. A Dutch friend told us about ten years ago that she hadn’t notified the French Tax authorities of the family bank accounts still held in Holland. She was fined €750 per account, regardless of the money in the account. We spoke to our accountant here and declared the accounts that we still had. It is the non-declaration that will catch you out. There is no problem or payment if you tell them. We closed all unnecessary accounts at that time.
Hope this helps.