Provisional assessment allows provisional tax payment with bond security and mandates final assessment within prescribed periods. Provisional assessment allows a taxable person unable to determine value or tax rate to request provisional payment; the proper officer must order provisional tax within ninety days and may require a prescribed bond with surety to secure payment of any difference. The proper officer must complete final assessment within six months, subject to limited extensions, and the registered person owes interest on unpaid provisional tax from the first day after the original due date until actual payment; refunds from final assessment attract interest under the refund provisions.