The Central Board of Indirect Taxes and Customs (CBIC) Released a notification with No. 63/2020–Central Tax on August 25, 2020. With this notification, CBIC informed that the changes which were made in Section 50 i.e inserting a proviso to Section 50(1), via section 100 of Finance (No. 2) Act, 2019 (23 of 2019) will come in effect from September 1, 2020.
Section 50 is related to the Interest on GST and It prompts charging interest on gross amount instead of the net amount. Now Government with this notification notified that interest will be applicable on the net amount with effect from 1st day of September 2020.
Amendment of Section 50
In section 50 of the Central Goods and Services Tax Act, in sub-section (1), the following proviso shall be inserted, namely
“Provided that the interest on tax payable in respect of supplies made during a tax period and declared in the return for the said period furnished after the due date in accordance with the provisions of section 39, except where such return is furnished after the commencement of any proceedings under section 73 or section 74 in respect of the said period, shall be levied on that portion of the tax that is paid by debiting the electronic cash ledger.”
It would be interesting to know here that the 39th GST council recommendations on Laws and Procedures presented that interest for delay in payment of GST 
Check out due dates of payment under GST for general and composition taxpayers in India. We have included penalty charges on late payment with interest should be charged on net cash tax liability with effect from 01.07.2017 (the law may be amended retrospectively) but the government nevertheless notified the provisions of 01.09.2020 instead of notifying the same notification with effect from 01.09.2017.
In a recent case of Prasanna Kumar Bisoi Vs Union of India, Hon’ble Orissa High Court on 21st August 2020 addressed the GST department for disposal of representation filed by the applicant as soon as possible, based on the decision taken at the 39th meeting of the GST Council 
The 39th GST Council meeting has been concluded on 14th March 2020 in New Delhi in the chairmanship of Union finance minister Nirmala Sitharaman and other panel ministers. Read more.
It is clearly observable that a rift is in between the taxpayers and the department regarding the date of applicability of the provisions of Proviso to Section 50 (1) of the Good and Service Tax Act, 2017.
The exact wording of the Notification No. 63/2020–Central Tax released on August 25, 2020, is engraved below.
We have made our pending payment tax liability for the month August 2017 after due date and also we made further delay to file GSTR3B. Our question is interest to be calculated, till the date of payment? or till the date of GSTR3B filing?
Till the date of filing
My return and tax payment was pending from Nov 19 if I file all my pending 3b return did I have pay interest on the net liability
Yes