You can include a VAT/Tax Number field on your cart page so that your customers can enter their VAT number just before checkout. These numbers will be stored as cart attributes. We will then automatically pick up this number saved in the order and show it in the invoice.

To add this field to your cart page, please follow these steps below -

Step 1: Click on ‘Online Store’ -> ‘Themes’ in your Shopify dashboard.

Step 2: Next, click on ‘Actions’ -> ‘Edit Code’

Step 3: Search for and click on the file labeled cart.liquid or cart-template.liquid (depending on your theme file)

b: Insert this snippet of code into this file in the section containing the ‘Update’ & ‘Checkout’ buttons -

<!-- PDF Invoice insert VAT ID -->
<input type="text" name="attributes[vat_id]" placeholder="Enter your VAT/TAX #" value="{{ cart.attributes['vat_id'] }}" />

Step 5: Click ‘Save’ in the file editor. That’s it!