Limitation period extension increases time for certain service tax reassessments by lengthening the statutory limitation. Amendment substitutes 'thirty months' for 'eighteen months' in sub-sections (1), (1A), (2A) and (3) of section 73, extending the period for reassessment in cases not involving fraud or suppression, and replaces the phrase in sub-section (4B)(a) with 'falling under' to adjust the clause's internal reference.