Annuity deposit deduction: reduces taxable salary for withholding, subject to allocation order and timing/declaration requirements. Annuity deposit is allowed as a deduction in computing total income for the assessment year in which it is required, limited where no deposit or insufficient deposit was made in the preceding financial year or permitted extended period; deduction is allocated first to salaries, then to earned income, and then to other heads. Payers of salary may deduct tax as if estimated salary were reduced by the annuity deposit amount required, subject to a proviso requiring a timely written declaration of intent to deposit where the payer's estimated income falls below a low-income threshold.