New tax regime limits exemptions and loss set offs, imposing prescribed rates with specific opt in and withdrawal rules. A new tax regime imposes a consolidated graded rate structure on specified taxpayers unless they exercise a prescribed option; total income is computed without certain statutory exemptions, deductions, allowances or set-off of losses and depreciation related to those excluded items, and such disallowed losses/depreciation are treated as fully given effect to and unavailable in later years. The regime permits taxpayers to opt in or withdraw under specified procedural limits, with special transitional modification for eligible IFSC units subject to conditions.