Interview Questions/System Design/Design a Subscription Billing System
IntermediateSystem-Design
30 min

Design a Subscription Billing System

BillingPaymentsFinance
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Interview Question

Design a recurring billing system with plan management, invoicing, dunning, and proration.

Key Points to Cover
  • Subscription plans: upgrades, downgrades, trials
  • Invoicing: tax, discounts, credits, proration
  • Payments: retries, dunning, failed payment handling
  • Ledger and reconciliation processes
  • Integrations: ERP, reporting, revenue recognition
Evaluation Rubric
Flexible subscription plan model25% weight
Accurate invoicing and proration25% weight
Robust dunning and retry strategy25% weight
Reliable ledger and reconciliation25% weight
Hints
  • 💡Handle mid-cycle plan changes carefully.
Common Pitfalls to Avoid
  • ⚠️Inaccurate or overly simplistic proration calculations, leading to billing disputes.
  • ⚠️Lack of a comprehensive dunning strategy, resulting in significant revenue loss from failed payments.
  • ⚠️Poorly designed plan upgrade/downgrade logic, causing customer confusion and frustration.
  • ⚠️Insufficient handling of edge cases like subscription cancellations mid-cycle or during free trials.
  • ⚠️Failure to properly account for taxes, discounts, and credits across all billing scenarios.
Potential Follow-up Questions
  • How to support usage-based billing?
  • How to handle international tax compliance?
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