What is a GST invoice and who should issue one?
The GST system has replaced the invoices such as tax invoice, excise invoice and retail invoices with one general GST tax invoice that has to be issued for all sales of goods and services.
As a GST registered dealer, you are obligated to provide invoices that are compliant with GST rules and regulations for all supply of goods and services.
GST tax invoice sample

Mandatory fields of a GST Invoice
From July 1st 2017, all tax invoices provided by GST registered suppliers need to contain the following fields:
Name, address and GSTIN of supplier;
Type of invoice - tax invoice, supplementary invoice or revised invoice;
Invoice date, series and number (just as before, a numeric series specific for a financial year);
Name, address and GSTIN (if registered) of invoice recipient;
HSN or SAC code for goods or services provided;
Description of goods or services provided;
Quantity and units of provided goods or services;
Total amount value of supply of goods or services;
Tax rate for every item;
Tax amount of CGST, SGST or IGST has to be shown in separate columns;
Place of supply and name of supplying state
Address of delivery (if it is different from the place of supply);
Statement describing if reverse charge is applicable.
Digital signature (or regular) of the supplier or an authorized person
Invoicing under GST - when should an invoice be issued?
In the case of Supply of goods:
Before or at the time of - removal of goods, if supply involves movement of goods;
Delivery of goods to the recipient, if supply does not require movement of goods.
In the case of Supply of services:
Within 30 days from the original date of supply;
*If a supplier is a bank or a financial institution, the invoice should be done within 45 days of the supply of service.
Note:If a person paying tax on reverse charge receives goods or services from an unregistered supplier, the receiver needs to issue an invoice on the date of receipt of the respective goods or services
How many copies of a tax invoice do you need to make?
In case of supply of goods, triplicate copies need to be made:
Original for recipient: issued to receiver
Duplicate for transporter: issued to the transporter. This is not mandatory if the supplier has an invoice reference number from the GST portal.
Triplicate for supplier: retained by the supplier
In the case of supply of services, duplicate copies need to be made:
Original for recipient: given to the receiver
Duplicate for supplier: kept by the supplier.
How should a tax Invoice for exports look like?
The export of goods or services is considered as a zero-rated supply. GST will not be levied on export of any kind of goods or services.
Additional, in export invoices, the following information regarding the recipient should be stated:
Name and address of recipient
Delivery address and country
Number and date of application for removal of goods for export
See the advantages of making export invoices with Sleek Bill
When should a tax invoice not be issued?
A registered person is not obligated to issue a tax invoice in two cases:
When the recipient is not a registered dealer AND
When the recipient does not require a tax invoice.
At the end of each day, a registered supplier has to issue a consolidated tax invoice for such supplies.
Note:In all other cases, the registered supplier is obligated to issue a tax invoice. By not issuing a tax invoice when mandatory, a supplier commits an offense under the GST Act and this offense will attract penalty.