Provisional assessment for refund permits summary provisional refund where regular assessment is likely delayed, with specified adjustment rules. Section 141A permits a summary provisional assessment for refund when a taxpayer's return claims tax paid exceeds tax payable and the Income-tax Officer believes a regular assessment will not be completed within six months; the officer may provisionally assess refunds after limited adjustments (arithmetical corrections, prima facie allowance or disallowance of claims, and giving effect to specified allowances, deductions and carried forward losses), prescribes assessment treatment for firms, and provides that provisional refunds are adjusted on regular assessment, do not prejudice merits, and are not appealable.