Interest concession for delayed GSTR-3B filings sets staggered nil-interest windows, then a uniform interest rate thereafter. The notification amends the proviso to prescribe time-limited interest treatment under section 50 for GSTR-3B filers: higher-turnover taxpayers receive nil interest for the first 15 days from the due date and 9% thereafter until 24 June 2020 for February-April 2020; lower-turnover Odisha-based taxpayers obtain staggered nil-interest windows for February-July 2020 for specified cutoff dates, with 9% per annum applying thereafter until 30 September 2020.