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Integrated Third-party OMS FAQ on GST 2.0
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Is there any requirement to update the ERP system for posting invoices/returns?

Yes, to handle returns when recalculate-tax is switched on in channel master, we are in process of releasing a patch soon.

Current version handling: We calculate latest GST rate as per the transaction date.
New WIP: We are releasing a patch to refer “Original Invoices date” as passed by OMS Provider to calculate the GST rate in case of returns.

What will happen to the e-commerce orders received before 22-Sep-25 but fulfilled on or after 22-Sep-25?

As per GST 2.0, any invoice generated on or after 22-Sep-25, new tax rates shall be applicable. Depending on the invoice date, your OMS provider should be calculating the tax rates. System will take the input of the tax rates as provided by your OMS provider while posting the invoice.

Note: In case recalculate-tax is set to yes in the channel master, then the system shall calculate GST as per defined in the ERP for the same.

How will returns be handled in e-commerce?

As per the understanding we have received, returns should work as follows:

  • For sales before 22nd Sep 2025 → Returns will follow the old GST rate as per the original invoice.

  • For sales on/after 22nd Sep 2025 → Returns will follow the new GST rate.

This ensures compliance and avoids mismatch between sale and return taxation.

You need to discuss with your OMS provider on how they calculate tax while processing the returns. System will take the input of the tax rates as provided by your OMS provider while posting the return.

Note: In case recalculate-tax is set to yes in the channel master, then the system shall calculate GST as per defined in the ERP for the same as per the “Original Invoice Date” passed by the OMS provider.

What is your recommendation on Recalculate-Tax in channel master?

When Recalculate-Tax is on,

  • then for all invoices the ERP system shall calculate the tax as per the transaction date being passed by the OMS provider.

  • then for all returns the ERP system shall calculate the tax as per the “Original Invoice Date” passed by the OMS provider. You need to double check with the OMS provider on what date they are passing in “Original Invoice Date”, i.e., in “parenIntgInvoiceDate” attribute of integration.

Having said this, you should ensure that tax calculation is being done properly in your OMS provider for both Invoices as well as Returns. It is important to note here that the physical Invoice which is sent to end customer is generated from OMS and thus the tax should be calculated properly in the OMS itself. This recalculate-tax provision was added to ensure that during transition phase (moving to new OMS provider) there isn’t mismatch while posting the transaction and ultimately reporting to GST department. This shouldn’t be treated as a default option.

Our returns are posted with new GST rate, what to do?

You will have to file GST returns carefully in case you plan to charge original tax rate by manually doing ledger adjustments and modifying the sale/return dump being used for GST returns.

You should also keep the document of the working attached to the ledger adjustments passed so that in future if any GST audit is there, you can present the same.