Debit Note/ Credit Note Time limit ?

Dithin Mathew (48 Points)

21 June 2017  
What should be the time limit for issuing the debit or credit notes in Gst laws ? The previous VAT system has been limited with three months from the date of purchase or sale are done. Please exaplain. what is the different advantages of Gst on comparing with VAT system?
What about the composition scheme ? how effect debit note and credit note to composition scheme.?