To make a tax invoice, you need to include specific details such as the name and address of the supplier and the customer, the GSTIN of both parties, a unique invoice number and date, a description of the goods or services, the quantity and value of the goods or services, the rate and amount of tax, and the total amount payable. You can create a tax invoice using invoicing software and templates or manually create one. It is important to ensure the accuracy and completeness of information on the tax invoice and comply with legal requirements to avoid penalties.