For Tax Invoices (B2B), is it mandatory to provide the customer with a PDF/A3 (with embedded XML) document or would the invoice in XML format suffice?

For Tax Invoices (B2B), is it mandatory to provide the customer with a PDF/A3 (with embedded XML) document or would the invoice in XML format suffice?

E-invoicing Resolution provides option to either share XML or PDF/A-3 (with embedded XML). If the buyer is able to process XML and agrees to receive file in XML format, then it is valid compliance to send XML.