Starting next week, new rates and new penalties will apply to six- and 30-month money market savings certificates.

While the interest rates will be higher, so will the penalties for premature withdrawal. In such cases, the holder must forfeit three months' interest on a six-month certificate and six months' interest on a 30-month certificate.

This means for the first time depositors risk losing a portion of their capital as well as accrued interest if they withdraw their money early. For example, if th purchaser of a $10,000 six-month certificate paying 9 percent annual interest cashed it in after one month, he or she would get back just $9,850. Similarly if the holder of a $5,000 30-month certificate paying 10 percent interest, cashed it in after one month, only $4,791 would be returned.

The federal financial regulators who devised the penalties rationalized that holders of certificates pegged to market rates should also be subject to market forces when they sell. Thus, when the holder of a money market certificate sells it before maturity to get a higher rate on a new certificate, that person can expect to incur a capital loss on the sale.