Launch a paid web app legally and safely

This guide is for UK solo developers and very small teams about to charge for a web app, whether a one-off purchase, a subscription or a SaaS tool for businesses. It assumes your security checks are done and covers everything else that turns code into a business: structure, terms, cancellation and refund rights, the coming subscription rules, UK GDPR, VAT for UK and EU customers, payment providers and the operations customers judge you on. By the end you will have a launch order, checkout wording, a privacy notice outline and a price-change notice ready to adapt. It is general information, not legal or tax advice; for your own situation, speak to an accountant or a solicitor who handles tech businesses.

What is inside

• Full step-by-step method9 detailed steps with decision points
• Ready-to-use templatesCheckout wording and confirmation email for immediate access · Price change notice to subscribers · Privacy notice outline
• Timed action plan8 stages from “6 weeks before launch” to “Before January 2027”
• Costly mistakes to avoid4 traps and what to do instead
• Complete checklist12 items to tick off
• Insider tips and fixes4 tips and 4 common problems solved

Step by step

1. Choose your business structure before the first sale

   If you are testing demand with modest revenue and low risk, operating as a sole trader is simplest: tell HMRC by registering for Self Assessment by 5 October after the end of the tax year in which you started, and check on GOV.UK whether Making Tax Digital for Income Tax applies to you. If customers will rely on your app for important data, you sign business contracts, or you want to keep business debts separate from your home and savings, a private limited company is usually the better fit, but it brings Companies House filings, director identity verification, annual accounts and Corporation Tax. Check your chosen name is free on Companies House and not too close to an existing trade mark on the Intellectual Property Office register. Open a separate business bank account from day one so your records and VAT position stay clear. Show your trading details on the site: your legal name or company name, a geographic address, an email address and, if you have them, your company number, registered office and VAT number.