Under GST Export would be treated as zero-rated supply. So if we export any goods or services or both it will be Zero rated. On Exports made IGST paid on export goods or the input tax credit proportionate to the goods and services consumed in goods exported under bond /LUT would be refunded.
Below are scope of export of goods and service under GST:

• Scope of Zero Rates Supplies:

1. The following two categories of supplies are recognized as Zero Rated Supplies (Sec16 of the IGST Act)

• Export of goods or services or both
• Supply of goods or services or both to a SEZ Developer or a SEZ Unit

Here we are discussing only Export of goods or services..

2. Export of goods means taking goods out of India to a place outside India (Sec 2(5) of IGST Act)
3. Export of services means the supply of any service when,

• the supplier of service is located in India;
• the recipient of service is located outside India;
• the place of supply of service is outside India;
• the payment for such service has been received by the supplier of service in convertible foreign exchange; and
• the supplier of service and the recipient of service are not merely establishments of a distinct person in accordance with Explanation 1 in Section 8 of IGST Act

Refund Rule and Provisions In Case of Export:
Under GST regime exports would be considered as zero-rated supply. Any person making zero rated supply (i.e. any exporter) shall be eligible to claim refund under either of the following options, namely:
(I) he may supply goods or services or both, subject to such conditions, safeguards and procedure as may be prescribed, on payment of integrated tax and claim refund of such tax paid on goods or services or both supplied, in accordance with the provisions of section 54 (Refunds) of the Central Goods and Services Tax Act or the rules made there under (i.e Refund Rules 2017).
(II) he may supply goods or services or both under bond or Letter of Undertaking, subject to such conditions, safeguards and procedure as may be prescribed, without payment of integrated tax and claim refund of unutilised input tax credit; or
Rule 96 of CGST Rules 2017 for option (I) above- Refund of integrated tax paid on goods exported out of India.-
(1) The shipping bill filed by an exporter shall be deemed to be an application for refund of integrated tax paid on the goods exported out of India and such application shall be deemed to have been filed only when:-
(a) the person in charge of the conveyance carrying the export goods duly files an export manifest or an export report covering the number and the date of shipping bills or bills of export; and
(b) the applicant has furnished a valid return in FORM GSTR-3 or FORM GSTR- 3B, as the case may be;
(2) The details of the relevant export invoices contained in FORM GSTR-1 shall be transmitted electronically by the common portal to the system designated by the Customs and the said system shall electronically transmit to the common portal, a confirmation that the goods covered by the said invoices have been exported out of India.
(3) GSTR-3 or FORM GSTR-3B, as the case may be from the common portal, the system designated by the Customs shall process the claim for refund and an amount equal to the integrated tax paid in respect of each shipping bill or bill of export shall be electronically credited to the bank account of the applicant mentioned in his registration particulars and as intimated to the Customs authorities.
(4) The claim for refund shall be withheld where,-
(a) a request has been received from the jurisdictional Commissioner of central tax, State tax or Union territory tax to withhold the payment of refund due to the person claiming refund in accordance with the provisions of sub-section (10) or sub-section (11) of section 54; or
(b) the proper officer of Customs determines that the goods were exported in violation of the provisions of the Customs Act, 1962.
(5) Where refund is withheld in accordance with the provisions of clause (a) of sub-rule (4), the proper officer of integrated tax at the Customs station shall intimate the applicant and the jurisdictional Commissioner of central tax, State tax or Union territory tax, as the case may be, and a copy of such intimation shall be transmitted to the common portal.
(6) Upon transmission of the intimation under sub-rule (5), the proper officer of central tax or State tax or Union territory tax, as the case may be, shall pass an order in Part B of FORM GST RFD-07.
(7) Where the applicant becomes entitled to refund of the amount withheld under clause (a) of sub-rule (4), the concerned jurisdictional officer of central tax, State tax or Union territory tax, as the case may be, shall proceed to refund the amount after passing an order in FORM GST RFD-06.
Rule 96A of CGST Rules 2017 for option (II) above. Refund of integrated tax paid on export of goods or services under bond or Letter of Undertaking.-
(1) Any registered person availing the option to supply goods or services for export without payment of integrated tax shall furnish, prior to export, a bond or a Letter of Undertaking in FORM GST RFD-11 to the jurisdictional Commissioner, binding himself to pay the tax due along with the interest specified under sub-section (1) of section 50 within a period of
(a) fifteen days after the expiry of three months from the date of issue of the invoice for export, if the goods are not exported out of India; or
(b) fifteen days after the expiry of one year, or such further period as may be allowed by the Commissioner, from the date of issue of the invoice for export, if the payment of such services is not received by the exporter in convertible foreign exchange.
(2) The details of the export invoices contained in FORM GSTR-1 furnished on the common portal shall be electronically transmitted to the system designated by Customs and a confirmation that the goods covered by the said invoices have been exported out of India shall be electronically transmitted to the common portal from the said system.
(3) Where the goods are not exported within the time specified in sub-rule (1) and the registered person fails to pay the amount mentioned in the said sub-rule, the export as allowed under bond or Letter of Undertaking shall be withdrawn forthwith and the said amount shall be recovered from the registered person in accordance with the provisions of section 79.
(4) The export as allowed under bond or Letter of Undertaking withdrawn in terms of sub rule (3) shall be restored immediately when the registered person pays the amount due.
(5) The Board, by way of notification, may specify the conditions and safeguards under which a Letter of Undertaking may be furnished in place of a bond.
(6) The provisions of sub rule (1) shall apply, mutatis mutandis, in respect of zero-rated supply of goods or services or both to a Special Economic Zone developer or a Special Economic Zone unit without payment of integrated tax.;

Relevant Date for Claiming Refund:

For claiming refund, application shall be made within 2 years from the relevant date. If refund of tax and interest has been paid under protest then the limitation of 2 years shall not be apply.

Refund Process under GST:

1. An Application form to claim a refund can be filed through the GSTN portal
2. Anacknowledgment numberwill be given to the applicant by the means of SMS or email when the application is filed electronically
3. The changes will be made to return and cash ledger and decrease the carry-forward input tax credit automatically
4. Refund application and relevant documents presented must be scrutinized and adhered accordingly within a period of 30 days offiling the refund application
5. The issue of unjust enrichment will be analyzed for reach refund application. In the case of non-qualification, the refund would be transferred to CWF (consumer welfare fund)
6. If a refund amount stated crosses the predetermined amount of refund then the file will through the pre-audit process for sanctioning the refund
7. Refund will be credited electronically to the account of an applicant via ECS, RTGS or NEFT
8. The application for refund can be made after every quarter
9. An amount less than 1000 is not eligible for the refund

Grant of Provisional Refund in Case of Zero Rated Supplies

GST law also provides for grant of provisional refund of 90% of the total refund claim, in case the claim relates for refund arising on account of zero rated supplies. The provisional refund would be paid within 7 days after giving the acknowledgement. The acknowledgement of refund application is normally issued within a period of 14 days but in case of refund of integrated tax paid on zero rated supplies, the acknowledgement would be issued within a period of three days.
The provisional refund would not be granted to such supplier who was, during any period of five years immediately preceding the refund period, was prosecuted.

Delay in Refund and its Process:

The refund application must be entertained within the period of 90 days and must be processed in the same time period. If in any case the application could not be processed within the given time framework, there is an 6 percent of interest recommended along with the refund amount.

Credit for Inputs Under Export Scheme:

Credit for inputs will be available once the exporter purchased the inputs for producing the goods to export and the credit will be shown in electronic cash ledger when he will file the monthly return (CREDIT AVAILMENT) and when he will export the goods and gets the export manifest, then he can file the application for refund. (CREDIT UTILIZATION)
The finance ministry has agreed to refund 90% of the duties paid by exporters in the process of manufacturing items for export within a period of seven days under the Goods and Services Tax (GST) regime.
The remaining 10% refund will be made after verifications by tax authorities.
Thus, the proposed GST regime mandates that all duties must be paid at the time of the transaction, while refunds can be obtained after exports.
For exporters, this could mean a working capital crunch as duties may get held up with tax authorities for months before a refund is processed.
As per Rule 89(4) of CGST Rule 2017 Proportionate credit in case goods/services are used partly for effecting taxable supplies and zero rated supplies and partly for effecting nontaxable supplies and exempt supplies

No refund of unutilized ITC would be allowed under the following cases:
If the unutilized ITC is for GST paid on goods exported out of India whichattract excise duty.
If the supplier of goods has availed duty drawback on the excise duty paid or claims the refund on the integrated tax paid on such supply.

Invoicing under Export (GSTR1_Excel_Workbook_Template-V1.0):

If IGST is involved on any exports from India, the Export Invoice has to be reflected an endorsement as Supply meant for Export on Payment of IGST or Supply meant for Export under bond without payment of IGST.
The contents in Export Invoice remain same except inclusion of following information:

1. An endorsement in Export Invoice as SUPPLY MEANT FOR EXPORT ON PAYMENT OF IGST or SUPPLY MEANT FOR EXPORT UNDER BOND WITHOUT PAYMENT OF IGST, as the case may be, and shall, in lieu of the details.
2. Name and address of the recipient
3. Address of Delivery
4. Name of the country of Destination
5. Number and date of application of removal of goods for Export (ARE-1)

Invoice will be issued in triplicate. Original for recipient, duplicate for transporter, triplicate for supplier.