If an invoice is issued on 2nd Oct at 4.00.00 AM in India.
in the XML we must send issue time as 23.30.00Z and issue date as 1st Oct?
Or issue time 23.30.00Z and issue date 2nd Oct?
Obviously it would be 22:30:00Z and 1st Oct in UTC then.
The question is so strange and funny, that people do not want to bother even to answer.
The short answer - do not use manual transformation, use library which will transform for you DateTime object from one timezone to another and you will not have to ask such questions
Best regards,
Sergei
@sergei.shishov , Thank you for the rebuking. 
I had known the answer always but few persons in my organization wouldn’t feel my answer is right and asked me to still ask and get ZATCA’ version. 