There is no single GST formula for every online order: the country, whether the goods are domestic or imported, and how delivery is treated all matter. First identify the applicable country and order route; then check whether the displayed price includes GST and whether the basket contains goods with different GST treatment.
What determines GST on an online order?
Buying online does not, by itself, change the GST rules. Singapore’s Inland Revenue Authority of Singapore (IRAS) says the transaction medium does not alter the rules for supplies, while imports and specified e-commerce transactions can have separate rules: IRAS guidance on GST for consumers.
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- Country: GST rates and rules differ by jurisdiction.
- Order route: A domestic purchase and an imported shipment may use different tax calculations.
- Goods: Some goods may be taxable while others are GST-free or otherwise treated differently.
- Delivery: The delivery amount may form part of the goods’ consideration, be apportioned across goods, or be treated as a separate service.
- Price display: A calculation using a GST-inclusive amount differs from one using a GST-exclusive amount.
The examples below are specific to Australia, Singapore and India. They illustrate why you must not apply one country’s rate or method to another country’s order.
How to calculate GST on domestic delivered goods in Australia
For an Australian order where all supplied goods are taxable and the amount is GST-inclusive, the Australian Taxation Office (ATO) says GST payable is one-eleventh of the total consideration, including delivery. The same treatment applies when delivery is separately charged for wholly taxable goods. See ATO ruling GSTD 2002/3.
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GST payable = total GST-inclusive consideration, including delivery ÷ 11
For example, if the GST-inclusive total for taxable goods and delivery is A$110, the GST component is A$10. This is an arithmetic illustration of the ATO’s formula, not a separate rate or rule.
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If the basket includes GST-free goods
Where taxable and GST-free goods are supplied together, delivery may need to be reasonably apportioned. If the delivery fee is separately charged, include the portion attributable to the taxable goods in the taxable amount; the portion attributable to GST-free goods does not become taxable merely because it is part of the same delivery.
| Australian order contents | GST treatment in the ATO ruling |
|---|---|
| All supplied goods are taxable | GST is 1/11 of total consideration, including delivery. |
| All supplied goods are non-taxable | No GST on the goods under this example. |
| Taxable and non-taxable goods together | GST is 1/11 of the taxable-goods price plus 1/11 of the delivery amount reasonably attributable to taxable goods. |
The characterization of delivery can also matter. The ATO ruling states: “Where you supply a delivery service that is a separate supply, or a separate part of a mixed supply, the supply of the service will be taxable regardless of whether it is associated with the supply of taxable or non-taxable goods.” The applicable result depends on the supply and facts of the transaction.
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How GST is calculated on an imported online order in Singapore
For Singapore imports, IRAS calculates GST on the cost, insurance and freight (CIF) value plus customs duties payable. Postage is included in freight. IRAS’s consumer guidance gives a 9% GST example: goods at S$450, insurance and freight at S$50, and customs duty at S$50 produce a GST base of S$550 and GST of S$49.50: (S$450 + S$50 + S$50) × 9% = S$49.50. The 9% rate is the one stated in IRAS’s current consumer guidance accessed in 2026; check the current rules for an actual purchase. Source: IRAS guidance on imported goods.
Import relief depends on shipment details
IRAS says air or post imports with a CIF value of S$400 or less generally receive import GST relief, except for intoxicating liquors and tobacco. The guidance also says GST may instead be charged at the point of purchase when the overseas supplier is registered in Singapore. Air or post imports above S$400 are taxed on the full goods value under the page’s table, while sea or land imports do not receive the stated relief. These thresholds and exceptions are Singapore-specific and may change.
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What India’s local-delivery rule covers
India’s Ministry of Finance states that local delivery services are taxable at 18% in its 2025 FAQ. The FAQ distinguishes who pays: a registered local delivery-service supplier pays GST when supplying directly or through an e-commerce operator; if the supplier is not liable to register and supplies through an e-commerce operator, the operator pays under section 9(5). This rule concerns local delivery services described by the FAQ, not every delivery fee attached to an online order. Source: Ministry of Finance FAQ.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to work out which calculation applies to your order
- Identify the country whose GST rules apply. Do not infer the rate from the retailer’s website or currency alone.
- Check whether the goods are domestic or imported. For imports, look for the country’s rules on freight, postage, insurance, customs duty and any relief thresholds.
- Confirm whether the listed price includes GST. The Australian 1/11 calculation above applies to GST-inclusive consideration.
- Check the GST status of each item. If taxable and GST-free goods share a delivery fee, the fee may need apportionment.
- Review how delivery is shown and supplied. A delivery amount included in the goods’ price, a separately charged delivery service and an import freight cost may be treated differently.
- Check the checkout or import assessment for who collects the tax. Depending on the jurisdiction and transaction, the seller, platform, delivery provider or customs process may be involved.
An exact amount for a particular order cannot be determined without its country, goods, price basis, seller and shipping route. Product-specific treatment, customs charges and marketplace collection can also affect the amount due.
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