Subscription Billing and Revenue Management Platform

We run a subscription business and until now we have handled billing by hand: analysts keep customers in spreadsheets, issue invoices one by one, chase late payments over email and reconcile everything at month end. This no longer scales. We need one system that owns the full lifecycle of a subscription, from the moment a customer picks a plan to the day we recognise the revenue, so the team works from a single source of truth.

The platform must support several pricing models side by side: flat monthly and annual plans, tiered pricing where the unit price changes with volume, and usage based metering. On top of that we need trials with automatic conversion, mid cycle upgrades and downgrades with correct proration, coupons, and a clean way to pause or cancel. Recurring invoices should be generated automatically, taxes applied by region, and failed charges retried through a configurable dunning sequence with a grace period before we suspend access.

Finally we care about reporting. Leadership wants live MRR, new and churned revenue, expansion and contraction, trial conversion and cohort retention, all reconciled against the invoices and payments behind them. We expect clean data models, an audit trail for every money movement, and idempotent webhooks from the payment gateway. Please describe your approach, the stack, how you handle proration and tax edge cases, and a realistic delivery plan.