Provisional assessment: provisional tax payment allowed with bond, followed by final assessment and interest consequences. Provisional assessment allows a taxable person unable to fix value or rate to seek payment of tax on a provisional basis, with the proper officer prescribing provisional rate or value and requiring a prescribed bond with surety or security to secure any difference. The proper officer must complete final assessment within a further statutory period subject to authorized extensions; interest is payable on provisional tax unpaid by the ordinary due date until actual payment and, if a refund arises from final assessment, interest on the refund is payable under the refund provision.