GST on Export of Services Calculator (LUT vs IGST Paid)

The GST on export calculator multiplies the invoice value by the IGST rate to get the tax paid upfront on the IGST route. It then counts the days from paying that IGST with GSTR-3B to the latest statutory dates for the 90% provisional refund and the final refund, and prices that delay at your cost of funds.

IGST = invoice value x IGST rate (0 under LUT). Days blocked = refund date - GSTR-3B payment date (20th of the month after the invoice, monthly filers). Provisional refund = 90% of IGST by filing date + 15 days + 7 days; balance 10% by filing date + 60 days. Cost = (90% x IGST x days to provisional + 10% x IGST x days to final) x cost of funds / 365.

For example, a ₹5,00,000 service invoice dated 5 October 2026 with an example IGST rate of 18% carries IGST of ₹90,000, paid with GSTR-3B by 20 November 2026. The client pays on 4 December and the refund is filed on 10 December. At the latest statutory dates, ₹81,000 comes back by 1 January 2027 (42 days) and ₹9,000 by 8 February 2027 (80 days). At an example cost of funds of 12%, that delay costs about ₹1,355. Under LUT, no IGST is paid.

1. Enter the invoice value in rupees, before GST.
2. Choose the route: export under LUT, or export with IGST paid.
3. Check the IGST rate for your service. The calculator starts at 18%.
4. Enter the invoice date and the number of days you expect between paying the IGST and filing the refund. The refund application needs the FIRC or BRC for the client's payment.
5. Enter your annual cost of funds, such as your overdraft interest rate.
6. Read the IGST payable, the refund dates and the cost of the money blocked, and compare it with the LUT route.

The result shows how much cash the IGST paid route ties up and for how long. Under LUT the upfront tax is zero, so nothing is blocked on the export itself. On the IGST route a larger invoice, a slower client or a late refund filing all increase the days blocked and the cost.

• IGST payable: The cash you pay with GSTR-3B for the invoice month on the IGST paid route.
• Provisional refund: 90% of the claim, due within seven days of the acknowledgement under the risk-based system, unless the officer records reasons to withhold it.
• Final refund: The balance, due with the refund order within 60 days of a complete application. Interest is payable for delay beyond 60 days.
• Cost of funds: An estimate of interest you pay, or lose, while the IGST is with the government. A figure close to zero means the timing barely matters for that invoice.

• Rates used: 18% is a default only. The 2017 GST Council schedule lists 18% for services not specified elsewhere, but rates depend on the service, so confirm yours in the current CBIC rate notifications.
• Timelines: Refund dates are the latest allowed by the rules: acknowledgement within 15 days of filing, provisional order within 7 days of acknowledgement, final order within 60 days. Actual dates can be earlier, or later if the officer finds deficiencies.
• IGST route: Since 1 October 2023, exporting on payment of IGST is open to the persons or supplies notified under section 16(4) of the IGST Act, so check that your service is covered. The calculator treats the full IGST as paid in cash; paying part from input tax credit lowers the cash blocked.
• Return frequency: GSTR-3B is taken as due on the 20th of the following month for monthly filers. Quarterly filers have different dates.
• Not covered: Export of goods, supplies to SEZ units, the refund of input tax credit under LUT (which depends on your own inputs and turnover) and interest on delayed refunds are not calculated.

• No LUT filed: Raising export invoices without IGST before an LUT is in place. The LUT must be furnished before export and is valid for the financial year in which it is filed.
• Wrong table: Reporting tax on exports outside Table 3.1(b) of GSTR-3B. The portal checks refunds against the tax shown in that table.
• Early filing: Filing the refund before the client pays. For services, the claim needs the bank realisation certificate or FIRC, and where payment follows the service, the two-year limit runs from the payment date.
• Rupee payments: Assuming any payment counts as export. Under GST, export of services needs payment in convertible foreign exchange, or in rupees where RBI permits it.
• Unpaid LUT invoices: Ignoring LUT invoices the client never pays. After the period in Rule 96A, the tax and interest become payable.

GST on export of services follows the zero-rating rules. Exports of services are zero-rated supplies under section 16 of the IGST Act. CGST Rule 96A governs the LUT. Rule 96(9) sends IGST refunds on services to Rule 89. Section 54 and Rule 91 set the refund deadlines, including the 90% provisional refund.

Related guides: gst on export of services, gst refund export of services, lut filing gst portal, what is igst refund.

Every rule and fee is linked to its official or first-party source below with the date it was checked. The full method is on the methodology page.

1. IGST Act, 2017, Section 16: Zero rated supply (CBIC tax information portal), s.16(1)(a) export is zero rated; s.16(3) refund of unutilised ITC under bond or LUT without payment of IGST (substituted w.e.f. 1 Oct 2023); s.16(4) Government may notify class of persons or supplies that may pay IGST and claim refund (checked 8 Oct 2026)
2. CGST Rules, 2017, Rule 96A: Export under bond or Letter of Undertaking, Rule 96A(1): LUT in FORM GST RFD-11 prior to export; 96A(1)(b) tax with interest if payment for services not received within one year or FEMA period, whichever later, plus fifteen days (checked 8 Oct 2026)
3. CGST Rules, 2017, Rule 96: Refund of integrated tax paid on goods or services exported, Rule 96(9): refund of IGST paid on services exported filed in FORM GST RFD-01 and dealt with under Rule 89 (checked 8 Oct 2026)
4. CGST Rules, 2017, Rule 89: Application for refund, Rule 89(1) RFD-01; 89(2)(c) invoices with BRC or FIRC for export of services; 89(4) ITC refund formula for zero-rated supplies under LUT (checked 8 Oct 2026)
5. CGST Act, 2017, Section 54: Refund of tax, s.54(1) two years from relevant date; s.54(6) 90% provisional refund for zero-rated supply; s.54(7) order within sixty days; Explanation 2(c) relevant date for exported services (checked 8 Oct 2026)
6. CGST Rules, 2017, Rule 91: Grant of provisional refund, Rule 91(2) substituted w.e.f. 01.10.2025 by Notification 13/2025-CT: RFD-04 within seven days of acknowledgement, based on system risk evaluation; officer may record reasons not to grant (checked 8 Oct 2026)
7. CGST Rules, 2017, Rule 90: Acknowledgement, Rule 90(2): scrutiny and acknowledgement in RFD-02 within fifteen days of filing; section 54(7) period counted from date of filing (checked 8 Oct 2026)
8. CGST Act, 2017, Section 56: Interest on delayed refunds, Interest at a rate not exceeding six per cent for delay beyond sixty days from receipt of application (checked 8 Oct 2026)
9. CGST Rules, 2017, Rule 61: Form and manner of furnishing of return, Rule 61(1)(i): GSTR-3B for each month on or before the twentieth day of the following month (checked 8 Oct 2026)
10. CGST Act, 2017, Section 39: Furnishing of returns, s.39(7): tax due paid not later than the last date for furnishing the return (checked 8 Oct 2026)
11. IGST Act, 2017, Section 2: Definitions, s.2(6)(iv): payment received in convertible foreign exchange or in Indian rupees wherever permitted by RBI (checked 8 Oct 2026)
12. CBIC Circular No. 8/8/2017-GST: Furnishing of Bond/LUT for exports, 4 October 2017, Para 2(b): LUT valid for the whole financial year in which it is tendered (checked 8 Oct 2026)
13. GST Portal FAQ: Refund on Account of Export of Services (With Payment of Tax), Ground 'Exports of services with payment of tax'; Statement 2 with BRC/FIRC details; refund limited to tax shown in Table 3.1(b) of GSTR-3B (checked 8 Oct 2026)
14. GST Council: Schedule of GST rates for services (2017), Item 36: all other services not specified elsewhere, 18% with full ITC (checked 8 Oct 2026)