If the CD has a term of more than one year and you don't post interest to the account until maturity, interest is taxable in the year that it is earned (accrued), and you must do a year-end information report to the IRS on from 1099-OID. A copy, of course, goes to your customer. There will be such a report for the year in which the CD is created, one for the year in which it matures, and one for each calendar year in between (if any).
If your reference to "notice" in your question refers to a maturity notice, you only have to send one out just prior to maturity. Read section
230.5 to determine when that notice has to be sent and what it needs to include (it will depend on whether the CD automatically renews).