How to integrate a subscription billing platform

The most actionable advice for setting up subscription billing is to choose a platform that handles both the payment processing and the complex logic of recurring cycles. For most UK startups, using a service like Stripe Billing, Paddle, or Chargebee is essential because they manage "dunning" (retrying failed cards), prorating upgrades, and providing a customer portal for cancellations automatically. Without this, you would have to manually track every customer's renewal date and send individual invoices, which is impossible to scale.

1. Choose your provider model

In the UK, you generally have two choices for how you handle payments and taxes:

• Payment Service Providers (e.g., Stripe): You are the seller of record. You get lower transaction fees, but you are responsible for calculating and filing VAT in every country where you have customers.
• Merchant of Record (e.g., Paddle, Lemon Squeezy): They act as the middleman. They sell the product to the customer on your behalf, meaning they handle all the VAT/tax compliance globally. This is often the preferred choice for small UK SaaS businesses to avoid international tax headaches.

2. Map your pricing to the platform

Once you have selected a provider, you need to recreate your subscription tiers within their dashboard. You will define your "Products" (the service you are selling) and "Prices" (the specific monthly or yearly costs). Ensure you set the currency to GBP as your primary base, but most platforms will allow you to offer multi-currency support to attract international customers.

3. Ensure SCA compliance

Since you are operating in the UK, your billing integration must support Strong Customer Authentication (SCA). This is a legal requirement that often requires customers to perform two-factor authentication (like a fingerprint or a code from their bank app) before a payment is authorised. Modern platforms like Stripe and Paddle handle this automatically through their hosted checkout pages.

4. Integrate the checkout flow

You have two main ways to put the billing system on your site:

1. Hosted Checkout: You redirect the user to a page hosted by the provider (e.g., Stripe Checkout). This is the easiest to set up and requires very little coding.
2. API Integration: You build the payment forms directly into your software. This keeps users on your site but requires significant development work and stricter security (PCI) compliance.

Pro Tip: Start with a Hosted Checkout. It is secure, mobile-responsive, and requires minimal maintenance, allowing you to launch your service much faster.

5. Set up a customer portal

Don't spend time building a page where users can update their credit card details or download invoices. Most subscription platforms provide a pre-built "Customer Portal." You simply provide a link in your app, and the user is taken to a secure area managed by the billing platform to handle their own account management. This reduces your support tickets significantly.

6. Test with "Test Mode"

Before taking real money, use the platform's test environment. All major providers offer "test card numbers" that allow you to simulate successful payments, declined cards, and SCA challenges. Run through the entire journey—from signing up to cancelling—to ensure the user experience is seamless.