Provisional assessment allows provisional tax payment with bond; final assessment, extensions and interest apply thereon. Where a taxable person cannot determine value or tax rate, they may request provisional assessment; the officer must allow provisional payment within ninety days and may require a prescribed bond with surety to secure payment of any difference between provisional and final assessments. The officer must pass final assessment within six months, subject to recorded extensions. Interest is payable on unpaid tax from the due date until actual payment, and refund interest on amounts arising from the final assessment is payable as provided by refund rules.