EPA is amending the Toxic Substances Control Act (TSCA) section 8(a) Inventory Update Reporting (IUR) regulations. The IUR currently requires manufacturers (including importers) of certain chemical substances listed on the TSCA Chemical Substances Inventory to report data on chemical manufacturing, processing, and use every 4 years. In this amendment, EPA is extending the reporting cycle, modifying the timing of the submission period, further clarifying the new partial exemption for specific chemicals for which certain IUR data are of low current interest, amending the petroleum refinery process streams partial exemption, amending the list of consumer and commercial product categories, revising the manner in which production volume would be reported, restricting reporting of processing and use information to domestic processing and use activities only, clarifying the polymer exemption definition, and removing a provision regarding the confidentiality of production volume within specified ranges.