Currently, having a default setting to enable VAT pricing is not a requirement of Shopify themes. However, we've included some tips here if you need to inform your customers about value-added tax (VAT) pricing.
Adding a message on the cart page
To help communicate VAT information, depending on your theme, you can either add a 'cart message' within the theme editor or alter the language files in order to include a note on your Cart page.
Instructions on how to add a cart page message
Adding a message on product pages
The simplest way to add a note to the Product page is by adding the note to the Description field in the product admin page by going into your Shopify Admin > Products > Select your product, and edit the description there. If you require a link to your shop's policies on the product page, you can also do that here.
To add a note beside or near the product price, you would need to add the note within the theme code. If editing the theme's code, we recommend creating a duplicate copy of your theme first for testing purposes.
Customization to show VAT prices on your product pages
Shopify has a customization article that involves editing the product prices within the liquid templates, but for products with variants, further customization is required to update the JavaScript.
Additionally, schema pricing for social sharing would need to be further customized.
Because of the extensive customization that would be required, we recommend hiring a dedicated developer who would be able to add in the additional code required and ensure that it complies with your requirements. We have a list of recommended Shopify Experts who specialize in our themes through our Services page.