Time limit for credit and debit note.

Sec 34(2)

Before 6 month from the end of financial year.
Means you can issue debit note or credit note of financial year 2018-19 upto 30th sept 2019

The credit note and debit note in relation to a particular transaction shall be issued within the end of September of the following financial year in which the supply has been undertaken or before the date of filing annual return whichever is earlier.

there is no time limit for issuing credit note/ Debit note under GST.

Bro/sister, there is any any direct provision in gst to curtail this issue, but in indirect means you can resolve this, that is section 34(2),
There are two phases dealing about credit note and debit note
1 . Issue phase
2 . Deceleration phase

Section - 34(2) deals about declaration phase, if you understand 34(2) then you will got solution to issuenc phase

The maximum time limit to dealer debit/credit note in return as per 34(2) is,
A)September of following financial year for SUPPLY MADE IN FINANCIAL year, or
B) Filing annual return for RELEVANT period

Highlights:- For supply made in the financial year and Relevant period

Notes:- If you issue debit note or credit note before the limit specified in 34(2) then only, you able to compute limit specified under 34(2) for decler in return

If you issue beyond the limits under 34(2),then there is no limits for declaration in return, suppose check it, if debit/credit note issued in December of 2018 for supplies made in financial year 2017-18,then your are not in situation to compute three limits specified under 34(2) for declaring in return

Conclusion :- maximum limits specified under 34(2) limits applicable to time limit for issuance of credit note or debit note