Getting your legal foundations right — from choosing a business structure to meeting your consumer protection obligations — protects you from personal liability and keeps HMRC and Trading Standards off your back as you scale.
Sole trader vs. limited company: the core decision
As a sole trader, you and the business are legally the same entity — registration with HMRC is free and takes minutes, and you pay Income Tax and Class 2/4 National Insurance on profits through Self Assessment. The major downside is unlimited personal liability: if the business runs into debt or is sued, your personal assets are technically exposed.
A limited company is a separate legal entity, registered with Companies House for a £50 online fee, offering limited liability that protects your personal assets in most circumstances. You'll pay Corporation Tax on profits (19–25% depending on profit level) rather than Income Tax, and you can pay yourself a mix of salary and dividends, which is often more tax-efficient once profits exceed roughly £30,000–£40,000 a year. The trade-off is more admin: annual accounts, a confirmation statement, and generally the need for an accountant.
Many UK online sellers start as sole traders to keep things simple while validating the business, then incorporate as a limited company once revenue and risk exposure justify the extra structure — there's no penalty for switching later, though you'll need to re-register for VAT and update supplier/payment processor agreements under the new entity.
Registering with HMRC and Companies House
Sole traders must register for Self Assessment with HMRC by 5 October following the end of the tax year in which they started trading — miss this and you risk a penalty even if you owe no tax. Limited companies must incorporate at Companies House first (this creates the company and its registration number), then separately register for Corporation Tax with HMRC within three months of starting to trade.
Whichever structure you choose, keep meticulous records of income and expenses from day one — bank statements, invoices, receipts for stock and packaging — because HMRC can request records going back several years, and reconstructing them retroactively is painful. A dedicated business bank account, even for sole traders where it isn't legally required, makes this dramatically easier.
VAT registration and thresholds
You must register for VAT once your taxable turnover exceeds £90,000 in any rolling 12-month period (this threshold is reviewed periodically, so check the current figure on GOV.UK before relying on it). Many e-commerce sellers voluntarily register earlier, because it allows you to reclaim VAT on stock, equipment and software purchases — worthwhile if you're investing heavily in inventory before significant sales volume.
Once registered, you must charge VAT (usually 20% standard rate, though some goods are reduced-rate or zero-rated) on UK sales, file returns (typically quarterly) via Making Tax Digital-compatible software, and issue VAT invoices on request. Selling into the EU or via online marketplaces introduces additional VAT complexity — see our companion piece on UK VAT and import duties for the detail.
Consumer protection law for online sellers
The Consumer Rights Act 2015 requires that goods sold online be of satisfactory quality, fit for purpose and as described — customers can request a repair, replacement or refund if they aren't. The Consumer Contracts Regulations 2013 give online customers a 14-day 'cooling off' right to cancel most orders for any reason, plus a further 14 days to return the goods once they've cancelled, and you must refund the original delivery cost (at the cheapest standard rate you offered) within 14 days of receiving the return or evidence of return.
Your website must clearly display your business name, registered address, VAT number (if registered), and contact details, along with a returns policy that meets or exceeds these statutory minimums — a returns policy that's more restrictive than the law allows is simply unenforceable and exposes you to Trading Standards complaints.
Data protection and the UK GDPR
If you collect any customer data — names, email addresses, order history — you're subject to the UK GDPR and Data Protection Act 2018. Practically, this means registering with the Information Commissioner's Office (a modest annual fee based on your size), publishing a privacy policy explaining what data you collect and why, obtaining clear consent for marketing emails (pre-ticked checkboxes are not valid consent), and having a process to fulfil data subject access and deletion requests.
Cookie consent is a related, often-overlooked obligation: if your site uses analytics or advertising cookies, UK PECR rules require a compliant consent banner before those cookies fire, not just an 'accept' button with no way to decline.
Advertising standards and marketplace rules
The Advertising Standards Authority (ASA) enforces the CAP Code across your website, social ads and email marketing — this covers everything from substantiating discount claims ('was £50, now £30' pricing must reflect a genuine prior price, per the Digital Markets, Competition and Consumers Act 2024's new drip-pricing and fake discount provisions) to disclosing paid partnerships and influencer content.
If you sell via Amazon, eBay or Etsy in addition to your own site, each marketplace layers its own seller policies on top of UK law — familiarise yourself with both, because a listing that's legally compliant can still be suspended for breaching marketplace-specific rules on trademark use, category restrictions or performance metrics.
Taking This Further
As with most things covered in Starting & Scaling, UK business registration, legal structures and compliance for online sellers works best when it's revisited periodically rather than decided once and forgotten. Many of the same principles come up again in Web Accessibility and WCAG Compliance for UK Online Stores: What You're Legally and Practically Required to Do, which is worth bookmarking for later.
For related reading: For the practical mechanics, see Understanding Earn-Outs and Deal Structures in an E-Commerce Sale.