According to the 21 Days Rule, if the Tax Invoice is issued within 21 days, the date of invoice will be considered as Time of Supply. However, if you are not able to issue the tax invoice after goods delivered or service performed within 21 days, then the Time of Supply will have to fall back to the date of Delivery.
Some companies may not be able to raise the tax invoice within 21 days from the DO e.g. Transportation company, Perhaps, you should consider to declare the Tax in the DO level.
With the help of GST Advisor, you can declare the delivery order’s GST in your tax return, without issue
the tax invoice within 21 days. The account posting entries will be updated as well. And at the time of
tax invoice issued, the declared tax amount will be removed from the tax invoice accordingly, so that
you will not pay for the same transaction 2 times.
Follow this User Guide learn more.