Reassessment limitation turns on the amended law at assessment time, and "calendar year" means 1 January to 31 December.

For reassessment under section 19(1), the limitation period is governed by the amended provision in force when the assessment is made and the reassessment power is invoked, not by the provision applicable during the turnover period sought to be reopened. A vested right against reassessment does not arise contrary to the law then operating at the time of assessment unless an accrued right is shown. The expression "calendar year" in section 19(1) means the year beginning on 1 January and ending on 31 December. On that construction, reassessment notices issued within that period are not barred by limitation.

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Issues: (i) Whether the period of limitation for initiating reassessment under section 19(1) was to be determined by the amended provision in force at the time of assessment and notice, or only by the provision as it stood during the period of turnover sought to be reassessed; and (ii) whether the expression "calendar year" in section 19(1) meant a period of twelve months from any date, or a year commencing on 1st January and ending on 31st December.

Issue (i): Whether the period of limitation for initiating reassessment under section 19(1) was to be determined by the amended provision in force at the time of assessment and notice, or only by the provision as it stood during the period of turnover sought to be reassessed.

Analysis: Section 19 operates as a machinery provision for reassessment of turnover that has escaped assessment or has been under-assessed. The relevant point for considering the applicability of the reassessment machinery is the stage when the assessment is made and the reassessment power is invoked, not merely the period to which the escaped turnover relates. The amendment substituting the words "date of order of assessment" for "expiry of such period" had come into force before the assessment orders were passed. Any vested right against reassessment could not arise contrary to the law then in force at the time of assessment, and no accrued right was shown to have been disturbed by the notices.

Conclusion: The amended limitation provision applied, and the notices were not barred on that ground.

Issue (ii): Whether the expression "calendar year" in section 19(1) meant a period of twelve months from any date, or a year commencing on 1st January and ending on 31st December.

Analysis: The expression "calendar year" had already been authoritatively construed to mean the year beginning on 1st January and ending on 31st December. The contrary view was not accepted, and the cited authorities did not displace that construction. On that meaning, the reassessment notices fell within the prescribed period.

Conclusion: "Calendar year" means the year from 1st January to 31st December, and the notices were within limitation.

Final Conclusion: The challenge to the reassessment notices failed because the amended limitation provision governed the case and the notices were issued within time on the accepted meaning of "calendar year".

Ratio Decidendi: For reassessment under a machinery provision, the limitation applicable at the time the assessment is made and the reassessment power is exercised governs, and the expression "calendar year" means the period from 1st January to 31st December.

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