Is it okay to give out our IOSS number to customers?

Shopify Discussion
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Topic summary

A merchant collecting VAT through IOSS received a request from a Finnish customer for their IOSS number, which the local post office needed to release a package. The merchant questions whether sharing this number directly with customers is safe or if it’s considered private information.

Key concern raised:

  • Sharing IOSS numbers openly could lead to misuse by unscrupulous parties
  • While some large retailers’ IOSS numbers are publicly available, caution is still advised

Recommended approach:

  • Investigate why the IOSS number wasn’t properly transmitted to the Finnish postal operator (Posti)
  • Common issue: Missing HS codes in the order at the shipping platform level causes Finnish customs software to drop all customs data, including the IOSS number
  • Customer then must manually file customs declaration

Important note:

  • Printing IOSS numbers physically on shipping labels serves no purpose and can endanger both the merchant and their fiscal representative
  • Ensure HS codes (minimum 6 digits) are included at the Shipstation order level to prevent data transmission failures
Summarized with AI on November 19. AI used: claude-sonnet-4-5-20250929.
1

We have been collecting VAT for quite a while now and our IOSS/GB numbers are always being electronically transmitted via Shipstation when we ship out orders. A customer from Finland who did pay for VAT reached out to us asking for our IOSS number as her post office required it in order to release her order.

I am wondering, are merchant VAT numbers considered private information or is this okay that we email the number to the customer? I am asking because when we were setting up VAT on Shipstation, I remember reading about not physically printing our VAT numbers on the shipping labels?

Thank you! :slightly_smiling_face:

Tina

2

Hi Tina,

this is not the best thing to do. If you openly start sending your IOSS number , it may be misused by unscrupulous people. Of course , you may say that Amazon’s IOSS number can be found on the net, but still. It might be safer to send your IOSS number to a customer in Finland , though.

Investigate the reason, why the IOSS number was not delivered/used by the postal operator. The most common cause with Posti (Finnish postal operator) is that there is missing HS code for your goods and the soft on the Finnish side drops all customs data (including IOSS number) and requests the customer to file the customs declaration manually. So make sure that HS code (at least 6 positions long) is in the order on the Shipstation level.

Printing IOSS number on the label does not help at all - not only it endangers you and your fiscal representative it also serves no purpose - no one will ever try to read it off the package.