Vacancy allocation: direct recruitment and promotion equally share Junior Time Scale posts under structured eligibility and feeder cadre rules. The rules constitute the Indian Revenue Service (Customs and Central Excise) Group 'A', specifying grades, authorised strengths and pay scales; recruitment to the Junior Time Scale is split between competitive examination by the Union Public Service Commission and promotion from specified Group 'B' feeder cadres with a prescribed promotion ratio. Promotions to higher grades are by selection or non functional placement subject to minimum service requirements listed in the schedules; probation, confirmation, seniority, non functional upgradation, committee compositions and service conditions are governed by the rules and Central Government instructions.