How is the Certificate of Deposit early withdrawal penalty calculated?

The amount of the early withdrawal penalty is based on the amount withdrawn and the term of your account. The penalty schedule is as follows:

Terms of 12 months or less = 90 days' dividends

Terms longer than 12 months = 180 days' of dividends 

The penalty is calculated as a forfeiture of part of the dividends that have been or would be earned on the account. It applies whether or not the dividends have been earned.