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Are all of your products set to charge taxes for the product? On each product, there will be an option to check off whether you want to charge taxes on a product. If this is unchecked, then the product won’t have taxes collected at checkout. If it’s checked, then you will have taxes charged at checkout.
You can edit a product and follow these steps to charge taxes on your products:
Login to your Shopify admin
Click on “Products” and click on the product you wish to edit
If you have no variants, scroll down to the Pricing section, then check off the box next to “Charge tax on this product”
If you have variants, scroll down to the variant you wish to edit and click on the variant, under the Pricing section, click the box next to “Charge tax on this variant”
Here’s a photo from my test store of what this looks like:
If you have multiple variants you want to charge taxes on, you can use the Bulk Editor to bulk add this option. The Bulk Editor is like a spreadsheet that will help you edit product details in bulk. From the product’s page, under the Variant section, click on “Edit Variants > Open Bulk Editor” then click on Add fields, then click on “Charge taxes” to add the “Charge taxes” column to the bulk editor. Check off the products you wish to charge taxes on and click the “Save” button at the top of the page to save your changes.
Sometimes you will need to override taxes on a product because your products are exempt from tax or have a lower tax rate. I recommend setting up overrides for your taxes by following our help doc with the instructions here: Override taxes. Have you tried these steps before?
If you haven’t checked our doc on setting up taxes in the UK, I encourage you to take a look here: Setting up taxes in the UK.
Is this what you were looking to accomplish? I am also curious, why do not want to charge VAT?