Advance tax estimate adjustment: notify assessing officer and submit revised head-wise income computation to challenge demand. Intimation under section 210(5) notifies the Assessing Officer that a notice of demand under section 156 for advance tax (pursuant to an order under section 210(3)/210(4)) has been served and contends the enclosed Form 28 estimate is excessive for specified reasons (arithmetical error, mistake apparent from record under section 154, capital gains loss, absence of income under section 2(24)(ix), or other reasons). The form requires a head-wise income estimate, set-offs and deductions, computation of tax and net balance, authorised signature per section 140, and prescribed attachments or declarations for firms and specified families.