All special assessments provided for in section 17-921 shall become due in fifty days after the date of the levy and may be paid within that time without interest, but if not so paid they shall bear interest thereafter until delinquent. Such assessment shall become delinquent in equal annual installments over such period of years as the city council or village board of trustees may determine at the time of making the levy. Delinquent installments shall bear interest at the rate specified in section 45-104.01, as such rate may from time to time be adjusted by the Legislature, until paid and shall be collected in the usual manner for the collection of taxes.