Having linked and confirmed just a bank account is not quite enough - you should also have a credit card as the card serves as your backup funding source and additional proof of ID. In some situations, PayPal may ask for a copy of a utility bill that shows both your name and address or may require a photo ID and/or your SSN.
It's the best way to confirm your identity - as everything is done online - you open a PayPal account and you say your name is John Smith - who knows who you really are - yes, you do but, no one else does. By providing ID info you have now validated your info - a bank account and credit card is the easiest method to prove you identity in the online electronic world. As you may own a bank account and card, you had to provide ID to open a bank account and apply for a card so your identity has already been vetted. PayPal then checks the info you provided against your bank account details and card details. If everything matches, name and address, PayPal will lift the limits on your account and you can then actually use the account as intended.
