Annual return gstr 9

As per Notification 15/2020 CT , it's being extended to 30/6/2020

Yes...
The annual return for FY 18-19 is extended to 30th Jun-2020...

(As per my view it will be extend another few days. wait on further updates).

Yes, the date have been extended to 30.06.2020. 

CBIC extends time limit for furnishing of the Annual Return (GSTR-9 and GSTR-9C) specified under section 44 of CGST Act, 2017 for the financial year 2018-2019 till 30.06.2020 vide Notification No. 15/2020-Central Tax Dated  23rd March, 2020.

In view of out break of COVID-19 and 21 days lockdown in the country further extention is also expected.

Yes, it's extended to 30june 2020

Where will be shown Debit note issued towards purchase return in GST 9 ??

Please guide

No not required to show purchases return in GSTR 9  as there is no column or table to report purchase or purchase or purchase return in GSTR 9