On March 15, 2018, Finance Act 2018 was granted Royal Assent by the UK Parliament. The Act makes several changes to direct and indirect taxation in the UK, including new requirements for online marketplaces to display their VAT registration number on the marketplace and, further, an extension of joint and several liability to these types of marketplace sellers for purposes of VAT.
All of the changes made under the Finance 2018 Act can be seen here.