The Panchayat Samiti in three-tier panchayat system is formed at

Concept: The 73rd Constitutional Amendment Act, 1992 inserted Part IX (Articles 243 to 243-O) into the Constitution, providing for a three-tier Panchayati Raj structure in most States: a village level, an intermediate (block) level, and a district level. Article 243B allows a State with a population not exceeding twenty lakh to skip the intermediate tier.

Application: Where the intermediate tier exists, it is constituted as the Panchayat Samiti (under the applicable state Panchayat Act, for example Section 68 of the Tripura Panchayats Act, 1993), functioning at the Block level, between the village-level Gram Panchayat and the district-level Zila Parishad. A Block groups together a defined cluster of Gram Panchayats for coordinated local planning.

Cross-check: The village level already hosts the Gram Panchayat, and the district level already hosts the Zila Parishad, so the Panchayat Samiti, where constituted, cannot be either; a sub-division is a general revenue-administration unit under district administration, not one of the Panchayati Raj tiers created under Part IX. Hence, Block Level is the correct tier.