Provisional assessment permits provisional tax payment when value or rate is uncertain, subject to bond, reassessment, and interest. Provisional assessment allows a taxable person unable to fix value or tax rate to seek provisional payment; the proper officer must order provisional payment within ninety days and may require a prescribed bond with surety securing payment of any difference between provisional and final tax. Final assessment must be completed within six months, subject to authorised extensions. Interest is payable by the registered person on any unpaid tax from the day after the original due date until payment, and interest on any refund resulting from the final assessment is governed by refund provisions.