# 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. {% hint style="warning" %} **Shopify Plus required.** VAT Validation uses Checkout UI Extensions, which require a Shopify Plus plan. {% endhint %} *** {% embed url="" %} ## 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" {% hint style="danger" %} **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. {% endhint %} This is a one-time setup in the Shopify Checkout Editor. ### Step 1: Open the Checkout Editor 1. Go to **Shopify Admin → Settings → Checkout → Customize** Or: **Online Store → Themes → Customize → select "Checkout and customer accounts" page** 2. 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" 1. With the **AOV VAT Validation** block selected, look at the right panel 2. Under **Checkout behavior**, find the toggle **"Allow app to block checkout"** 3. **Turn it ON** {% hint style="info" %} 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. {% endhint %} ### Step 3: Save Click **Save** in the top right of the Checkout Editor. {% hint style="success" %} **Done!** You only need to do this once. After enabling, all your VAT validation rules will be able to block checkout automatically. {% endhint %} *** ## 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**. *** {% embed url="" %} ## Step 3: Configure VAT field settings | Setting | Description | | --------------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | **Rule name** | A descriptive name (default: "VAT number validation") | | **Status** | **Active** — rule applies at checkout. **Test mode** — only triggers for email `aov@testing.com`. **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") | {% hint style="info" %} **Tip:** Start with **Test mode** status to verify the rule works correctly before activating it for all customers. Use `aov@testing.com` as the checkout email to see it in action. {% endhint %} *** {% embed url="" %} ## Step 4: Configure error messages Two error messages control what buyers see: | Error | When it shows | Default message | | ------------------------ | --------------------------------------------------------------- | --------------------------------------------------------------- | | **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. *** {% embed url="" %} ## Step 5: Set conditions (optional) By default, the VAT field appears for **all checkouts**. Expand the **Conditions** section to narrow the scope. | Condition | Description | | -------------------- | ----------------------------------------------------------------------------- | | **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. {% hint style="info" %} **Example:** Shipping country = Germany, France, Italy + Customer tag = `B2B` → VAT field only appears for B2B customers shipping to those 3 countries. {% endhint %} *** ## Step 6: Save the rule Click **Save** (top right). The rule is now active based on its status. *** {% embed url="" %} ## How format validation works When a buyer enters a VAT number, the system automatically validates the format based on their **shipping country**: | Scenario | Result | | ---------------------------------------------------------------- | ---------------------------------- | | 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.). {% hint style="info" %} **Lowercase is fine.** If a buyer types `de123456789`, the system automatically converts it to uppercase before validating. {% endhint %} *** ## FAQ {% embed url="" %} {% embed url="" %} **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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://help.aov.ai/aov.ai-checkout-upsell/checkout-validations/vat-validation.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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