For 30 days after the filing of the second original assessment list in the office of the county treasurer pursuant to Section 51254 the assessment shall not bear interest, except as provided by Section 51511, and, if bonds have not been authorized and sold on the basis of the assessment, any landowner may pay in lawful money of the United States, or approved warrants of the district, all or any part of the principal and interest of the assessment on any parcel.