Business enterprises are required to pay MSMEs within 45 days, as per section 15 of the MSMED Act, 2006, depending on the presence of a written agreement. In case there is no written agreement, payment should be made within 15 days. In case there is a written agreement, payment shall be made as per the agreed-upon timeline, not exceeding 45 days.
In the case of late payment to an MSME, interest is applicable. Compound interest at the 3 times the bank rate notified by the Reserve Bank of India (RBI).
Source: https://cleartax.in/s/section-43bh-of-income-tax-act