VAT Validation
Collect and validate VAT numbers at checkout. Require buyers to enter a valid VAT number before completing their order — with automatic format validation for 40+ countries.
Shopify Plus required. VAT Validation uses Checkout UI Extensions, which require a Shopify Plus plan.
What it does
VAT Validation adds a VAT number input field to your checkout page. You control:
Required or Optional — force buyers to enter a VAT number, or let them skip it
Format validation — automatically checks VAT number format based on the buyer's shipping country (40+ countries supported)
Custom error messages — show clear, localized errors when the field is empty or the format is invalid
Conditions — only show the VAT field for specific countries or customer tags (e.g., B2B, wholesale)
The VAT number is saved to the order note — accessible in Order admin and Shopify API.
Before you start: Enable "Allow app to block checkout"
Required setup. Without this step, the VAT validation rule will not block checkout — buyers can skip the field even when it's set to Required.
This is a one-time setup in the Shopify Checkout Editor.
Step 1: Open the Checkout Editor
Go to Shopify Admin → Settings → Checkout → Customize Or: Online Store → Themes → Customize → select "Checkout and customer accounts" page
In the left sidebar under Main, find and click the AOV VAT Validation block
If you haven't added it yet: click "Add block" → scroll to AOV.ai Checkout Upsell → select AOV VAT Validation
Step 2: Turn on "Allow app to block checkout"
With the AOV VAT Validation block selected, look at the right panel
Under Checkout behavior, find the toggle "Allow app to block checkout"
Turn it ON
The description reads: "Orders will be rejected if customer information is missing or invalid." This is exactly what enables the VAT validation to block checkout when the buyer leaves the field empty or enters an invalid format.
Step 3: Save
Click Save in the top right of the Checkout Editor.
Done! You only need to do this once. After enabling, all your VAT validation rules will be able to block checkout automatically.
Step 1: Go to Checkout Validations
In the app sidebar, click Checkout Validations. You'll see the list of all validation rules.
Step 2: Create a VAT validation rule
Click Create validation (top right), then select VAT Validation.
Step 3: Configure VAT field settings
Rule name
A descriptive name (default: "VAT number validation")
Status
Active — rule applies at checkout. Test mode — only triggers for email [email protected]. Expired — saved but not applied.
Field requirement
Required — buyer must enter a valid VAT number. Optional — buyer can skip, but if entered, must be valid format.
Field label
Label shown above the input at checkout (default: "VAT number")
Tip: Start with Test mode status to verify the rule works correctly before activating it for all customers. Use [email protected] as the checkout email to see it in action.
Step 4: Configure error messages
Two error messages control what buyers see:
Empty field error
Field is Required and buyer leaves it empty
"Please enter your VAT number to continue."
Invalid format error
Buyer enters a VAT number that doesn't match the country format
"The VAT number format is invalid. Please check and try again."
Errors display directly below the VAT input field at checkout. Maximum 150 characters each.
Step 5: Set conditions (optional)
By default, the VAT field appears for all checkouts. Expand the Conditions section to narrow the scope.
Included product
VAT field only appears when cart contains specific products or variants
Excluded product
VAT field hidden when cart contains specific products or variants
Subtotal value
VAT field only appears when cart subtotal meets a threshold (>, >=, <, <=, =)
Customer tag
Only show for customers with specific tags (e.g., B2B, wholesale)
Shipping country
VAT field only appears when buyer ships to specific countries
All conditions use AND logic — every condition must be true for the VAT field to appear.
Example: Shipping country = Germany, France, Italy + Customer tag = B2B → VAT field only appears for B2B customers shipping to those 3 countries.
Step 6: Save the rule
Click Save (top right). The rule is now active based on its status.
How format validation works
When a buyer enters a VAT number, the system automatically validates the format based on their shipping country:
Buyer ships to Germany, enters DE123456789
✅ Valid — matches Germany's format
Buyer ships to Germany, enters ABC123
❌ Invalid — error shown
Buyer ships to a country without a format rule (e.g., Australia)
✅ Any non-empty input accepted
Buyer changes shipping country mid-checkout
Format re-validates automatically
The system supports 40+ countries including all EU member states and major non-EU European countries (UK, Switzerland, Norway, etc.).
Lowercase is fine. If a buyer types de123456789, the system automatically converts it to uppercase before validating.
FAQ
Q: What happens if the buyer uses Apple Pay or Google Pay? A: VAT field does not appear for accelerated checkout methods (Shop Pay, Apple Pay, Google Pay). These checkouts proceed without VAT collection.
Q: Can I have multiple VAT validation rules? A: Yes. Each rule can target different countries or customer segments with different settings.
Q: Where is the VAT number stored after checkout? A: In the order note (format: VAT: DE123456789). You can view it in the Order detail page in Shopify Admin or access via Shopify API.
Q: Do I need Shopify Plus? A: Yes. VAT Validation uses Checkout UI Extensions, which require a Shopify Plus plan.
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