Change in Invoice Series

Rahul Pandey Amdehi (CA Practice) (24 Points)

02 February 2019  
Hello to All,

I am facing a problem related Invoice series, because one of my friends in hotel industry has two Bill Book (Bill of Supply and Tax invoice) and he is issuing two bills, Bill of Supply for Nil rated supply and Tax invoice for the taxable supply.
but now he want to install billing software, and using this software they can issue only one invoice.

so my question is that, Can he change the Invoice series in this financial year or not. ?