GST Valuation Rules: How to Determine the Correct Taxable Value

In most business transactions, calculating the Goods and Services Tax (GST) is simple: you take the price you charged the customer (the "Transaction Value") and multiply it by the tax rate.

However, what happens if you sell a car to your sister's company at a 50% discount? What if you exchange a new laptop for an old one plus some cash? In these cases, the "Transaction Value" is not a fair representation of the true value of the supply.

To prevent tax leakage through artificial price manipulation or barters, the law provides a set of GST Valuation Rules. These rules allow the government to override your invoice price and determine a "notional" value for tax purposes.

This guide explains Section 15 and the specialized Valuation Rules (Rules 27 to 35) for the 2026 Assessment Year.

The Foundation: Section 15 and Transaction Value

Under Section 15(1) of the CGST Act, the value of a supply is the Transaction Value—the price actually paid or payable—provided two non-negotiable conditions are met:

1. The supplier and the recipient are not related.
2. Price is the sole consideration for the supply (no barter, no hidden exchanges).

If both conditions are met, the value shown on your tax invoice is legally accepted.

What Must Be Added to the Value?

Under Section 15(2), you must include the following in your taxable value even if they are listed as separate line items:

• Any taxes, duties, and fees levied under other laws (like Municipal taxes).
• Amounts the supplier is liable to pay but are paid by the recipient.
• Incidental expenses like commission, packing, and insurance charged before delivery.
• Interest or late fees for delayed payment of consideration.

When Do the Valuation Rules Activate?

If you fail the two conditions of Section 15 (i.e., you are related or there is a barter), you must use the GST Valuation Rules (Rules 27 to 35).

Rule 27: Value when Consideration is not Wholly in Money

This applies to barters or exchange offers (like a mobile phone exchange). The value will be the Earliest of:

1. Open Market Value: The full price someone else would pay for the same item in cash.
2. Sum of Money + Non-monetary Value: Cash paid plus the market value of the exchanged item.
3. Value of Supply of Like Kind and Quality.

Rule 28: Transactions with Related Persons or Distinct Persons

This is the most common audit trigger. "Related persons" include directors, family members, or companies where you hold 25% or more shares. "Distinct persons" include your own branches in different states.

The Open Market Rule: The value must be the Open Market Value. The "Pure ITC" Relief: If the recipient branch/related person is eligible for Full Input Tax Credit, you can declare any value on the invoice (even zero or ₹1), and the government will accept it as the taxable value. This is a massive relief for inter-branch transactions.

Rule 30 & 31: The Fallback Methods

If neither Rule 27 nor Rule 28 works, you use the following in order:

• Cost-plus Method (Rule 30): 110% of the cost of production or acquisition.
• Best Judgement Method (Rule 31): A "reasonable" value determined using general principles consistent with these rules.

Specialized Valuation Scenarios

The government has notified specific values for certain industries to simplify compliance:

• Air Travel Agents: 5% of basic domestic fare or 10% of international fare.
• Life Insurance: The gross premium minus the amount allocated for investment.
• Second-hand Goods (Margin Scheme): Tax is paid only on the Profit Margin (Sale Price minus Purchase Price). If there is a loss, the tax is zero.

Legal Reference

Relevant Law: Section 15 of the CGST Act, 2017 defines Valuation. Chapter IV of the CGST Rules, 2017 (Rules 27 to 35) provides the specific mathematical methods for determining value.

Common Mistakes with GST Valuation

1. Excluding Subsidies from Product Price: If you receive a subsidy from a private NGO to sell a product cheaper, that subsidy amount must be added back to your taxable value. (Note: Subsidies from the Central or State Governments are exempt and not added).
2. Under-valuing Inter-branch Transfers: A company in Noida sends spare parts to its Chennai branch. Because it is a "Distinct Person" under Section 25, they must issue a GST invoice. If the Chennai branch sells exempt goods and cannot take full ITC, the Noida branch must use the Open Market Value, not the cost price.
3. Forgetting Interest on Delayed Payments: If a customer pays 3 months late and you charge them ₹5,000 as "late fee interest," that ₹5,000 is not a separate financial service—it is part of the original supply value. You must pay GST on that ₹5,000 at the same rate as the main product.

Conclusion

GST Valuation is designed to ensure that the government doesn't lose revenue due to non-market pricing. While the "Transaction Value" is the default for 99% of business, any transaction involving family, related companies, or barters requires a documented "Valuation Report" in your records to show how you calculated the tax. To stay compliant in 2026, always check if the recipient of your related-party invoice is eligible for full ITC before deciding on a nominal valuation.