E invoicing mandate: non e invoices will not be treated as valid and may attract penalties; register on the portal. A mandatory e Invoicing requirement requires taxpayers above the prescribed turnover threshold to generate e Invoices from 1 April 2022; invoices issued otherwise shall not be treated as an invoice. Non compliance may attract penalties and other GST law actions, and taxpayers are advised to register on the e Invoice portal, obtain an Invoice Registration Number and use provided tools and guides to ensure compliance.