Excess Tax paid

Anshuman Basu (account -GST) (1556 Points)

30 September 2020  
We generate invoice to our client for the month of August 2018. And according to we paid tax. (Suppose Invoice Value 118/- Taxable Value 100/- and CGST+SGST 9/- each)
In the month of January 19, we came to know that our client rejected the said invoice for technical ground.
We issued credit note for the month of January 2019 to him and Tax amount CGST+SGST 9/- each; we consider as our ITC and show in our GSTR3B in column no 4(A).

Please note we had no sales from December 18 to Onward. naturally we hadn't scope to adjust excess tax paid.
The problem is, when we are going to fill 18-19 GSTR9, we could not see the tax amount CGST+SGST 9/- each in column no 8(A) GSTR2A of Annual Return. Naturally Negative Figure is come in Column No 8(D) of GSTR9.
Now question is 

1/-what is the treatment of above scenario in GSTR 9?
 2/-What is procedure to adjust excess tax paid,?