There are two points I would like to add to "Investing for College" (Your Money, July). First, there are tax-exempt zero-coupon bonds sold in the municipal bond market. They are exempt from federal income taxes, and if you live in one of the majority of states that exempt municipal bonds, they are double exempt.

Second, besides the risk of a corporation or municipality not being able to pay principal at maturity, there is the risk of loss of principal if an investor is forced to sell the bond prior to maturity. Zeros are very volatile, and when interest rates rise, they decrease significantly in value.