Deductibility timing tightened: late payments to micro and small enterprises fall within timing rules and enterprise definitions aligned with MSME law. The amendment modifies timing-based deductibility by permitting the Government to notify classes of non-banking financial companies, inserts a clarifying connective in an existing clause, adds a provision subjecting late payments to micro or small enterprises (as defined in the MSME statute) to the timing rule, and adjusts the proviso to exclude that new clause from the proviso's exceptions while updating the enterprise definitions to mirror the MSME Act.