Is e-invoice mandatory for all businesses?

Only for taxpayers above notified turnover thresholds (and certain categories). Others may issue invoices without IRN unless they opt in.

Invoice Reference Number — a unique ID from the Invoice Registration Portal after successful e-invoice upload.

Letter E

E-Invoice

Digitally authenticated invoice registered through the GST/IRP system with an IRN.

Calculation / formula

After IRN generation, the invoice is valid for GST compliance; QR code and IRN appear on the document.

Is e-invoice mandatory for all businesses?: Only for taxpayers above notified turnover thresholds (and certain categories). Others may issue invoices without IRN unless they opt in.
What is IRN?: Invoice Reference Number — a unique ID from the Invoice Registration Portal after successful e-invoice upload.