GSTR1 and GSTR3B

Its Must Be Same 

I was working in public sector bank in india. as per rules at the time of resignation , employee has to serve
3 months notice period, otherwise he has to pay the salary for the notice period. at the time of my resignation
1.5 months back, I had given notice
of 10 days and paid salary of 80 days along with 18% gst. kindly guide me whether gst is applicable fo
r that and if not whether I can get refund of the same.

Further I have purchased the furniture from the furniture allowances from the bank and at the time of my resignation I had paid the depreciated value of the furniture to the bank. now after a period of1.5 months they are asking me to pay gst on the same.kindly guide me whether gst is applicable in subject case.