Can a creditor charge interest on a charged off account?

Your debts will continue to accrue interest persuant to the terms of the ever changing contract. Yes, the account is closed, you cannot charge against your account anymore. You can procede several different ways from here on out. If the debt has passed the statute of limitations, you could send a complete cease and desist letter, forbidding any future communications. I would only go this way if you are sure that the SOL has fully elasped. If you do this and the SOL is still in effect, expect to see a summons shortly after. You could attempt to work out a payment arrangement, but be aware that this will restart the SOL clock.

The entry will still appear on your credit report, until seven years after you defaulted.

Morningstar is right. The term charged off just means "charged against a loss reserve." A company's loss reserve is a certain portion of their total receivables that they earmark for bad debt. When they charge your account against their reserve, it just means they are not counting your balance as an asset anymore. However, it is still a legal obligation, and it will still earn interest according to the terms of the contract.