California Code, Streets and Highways Code - SHC § 6464

The legislative body conducting the proceedings may elect, in the resolution of intention, to have the redemption provisions of said bond provide a premium of 5 percent of the unmatured principal.  In such case, the words, “together with a premium of 5 percent of said unmatured principal” shall be added after the redemption clause in the bond form, and Section 6447 shall be deemed to require the property owner to pay a like sum in order to pay and discharge such lien.

As used in this section, “unmatured principal” means those installments of principal that are due to be paid at future dates and for which no corresponding payments of interest will be payable pursuant to the provision of Section 6447.