It's not easy to write a blog post about Brexit. Let's keep it short and with links to the sources to trust: the UK Gov. websites about Brexit changes.‌‌‌‌

Let's assume these 3 points:
You are on Shopify, Prestashop or WooCommerce (not on a Marketplace like Amazon or ebay).
You have some customers (not BtoB) in the UK.
You ship orders from outside the UK.

1. Order is not exceeding £135 in value (182 USD / 231 CAD / 240 AUD / 242 SGD / 18,800 JPY). You are required to charge and account for the UK VAT during checkout and register and account for the VAT to HMRC. This is not easy and might require a different blog post (and Shopify has a good one about it).‌‌‌‌

2. Order is exceeding £135 in value: your customer in the UK can pay for VAT and other customs fees. More details about these rules here. Not really a change here, especially for outside of EU sellers. You ship an order and the customer may have to pay these fees to the carrier at delivery.


So, let's get back to number 1 here. Because if the orders you ship to the UK cost less than  £135, you will have one more reason to think that Brexit was a terrible idea. Depending on the countries you are selling to the UK,  you will have to add the respective VAT registrations within your store admin. Therefore, it is recommended that you review your tax settings in your store and make the necessary changes.

Lots of question will be answered a bit later because carriers and sellers probably need to "see" these new rules in action:
-What happened if you don't register for VAT but ship orders not exceeding £135 to the UK?
-Does it make sense to ship DDP (Delivery Duty Paid) to the UK orders not exceeding £135?
-Should I setup a minimum order value from £135 for UK customers?

Stay tuned, we don't know everything yet.