Customer details, VAT validation, and the OSS setting

Historical retrospective - September 2025 to March 2026
This article was written afterwards and describes the feature as it worked during the stated periods.

The customer’s country, customer type, and registration details are used in checkout and invoicing. Enter them accurately so validation and the VAT-zone logic for your setup have the right basis.

Customer and checkout

Choose the customer’s country in the customer or checkout form and complete the fields required for the selected customer type. Country affects the address, available currencies, and which registration details may be relevant. It is a business change to the customer, not just checkout text; correct the customer record too when the source data was wrong.

For an EU business, a VAT number can be validated before the relevant invoicing proceeds. A country that cannot be validated or a missing registration number can leave checkout or invoicing incomplete. Alunta is not a tax adviser: use your accounting setup and adviser to decide the correct treatment.

OSS

If the team is VAT-registered in an EU country and sells to consumers in other EU countries, the OSS setting can be enabled in invoicing settings. It is a product setting for B2C invoicing; it does not change B2B reverse charge. With e-conomic, country VAT zones must also be configured correctly in the integration.

Does OSS apply to Danish customers? The setting is for cross-border EU B2C sales; Danish treatment follows your specific setup.

Is validation tax advice? No. It checks data and applies the selected setup.

See the checkout and self-service guide (Markdown file, AI agent-friendly).