E Invoice implication

Non-issuance of e-invoice is an offence under GST and thus attracts penal provisions. Below are some of the penalties for non-issuance of invoice or issuance of incorrect invoice:

Penalty for non-issuance of invoice- 100% of the tax due or Rs.10,000, whichever is higher.
Penalty for incorrect invoicing is Rs.25,000.

Is normal invoice is valid???

If turnover exceeds 500 crores then normal invoices is not applicable only e-invoice is mandatory

Sir I am asking is normal invoice is valid/not????...

No............ As per Rule 48(5) prescribes if Sub rule(4) is applicable then normal invoice is not the valid invoice.

Note : As per Notification 70/2020 CT amending Notification 13/2020 , taxpayer whose aggregate turnover in ANY preceding FY exceeds 500 crore (Now from 1/4/21 it's 50 crore) is required to issue E-invoice .
kindly note if in mid of Fy turnover get exceeded then the E-INVOICE provision will be applicable from subsequent FY.

Thank you sir

As per GST acct, if an assessee who is required to issue e-invoice fails to raise e-invoice, then the tax invoice might be considered as invalid. 

This attracts a penalty of Rs 10000 to 25000 per invoice

Normal invoices are not valid

Penalty for non-issuance of invoice- 100% of the tax due or Rs.10,000, whichever is higher. Penalty for incorrect invoicing is Rs.25,000. Read more on e-invoice under GST