You should generally match your CD maturities with your financial needs. For example, if you're putting a down payment on a house in 18 months, you'd want a CD maturity of 18 months or less. If you're constructing a ladder, you might want to spread your money out over CDs that mature in consecutive years, say every year for one to 10 years. As each CD matures, you'll buy a new 10-year CD to keep your ladder intact.