Model SaaS Subscription Billing

Scenario

A SaaS company wants to generate a subscription management system that handles trials, paid plans, seats, entitlements, invoices, failed payments, and cancellation.

Events

• Trial Started
• Subscription Activated
• Seat Added
• Plan Changed
• Invoice Issued
• Payment Failed
• Dunning Started
• Entitlements Suspended
• Subscription Cancelled

Aggregates

• Subscription: plan, lifecycle, renewal date, cancellation state.
• Account Entitlements: features and limits available to the account.
• Invoice: issued amount, due date, payment state.
• Dunning Case: payment recovery workflow and communications.

Commands

• Start Trial
• Activate Subscription
• Add Seat
• Change Plan
• Issue Invoice
• Record Payment Failure
• Start Dunning
• Suspend Entitlements
• Cancel Subscription

Rules

• A subscription cannot be activated without a billing account.
• A seat cannot be added beyond the account’s plan limit unless overage billing is enabled.
• A plan downgrade cannot remove features currently required by active commitments without confirmation.
• Entitlements can only be suspended after the configured dunning window expires.

Policies And Saga

• When Subscription Activated, enable account entitlements.
• When Plan Changed, recalculate entitlements and billing schedule.
• When Payment Failed, start dunning if the account is not already in dunning.
• When Dunning Started, schedule payment retry and send customer notification.
• Use a Dunning Process saga to track retries, notifications, deadlines, recovery, suspension, and cancellation.

Read Models

• Account Subscription Summary: current plan, status, renewal, seats, entitlements.
• Billing Timeline: invoices, payments, failures, refunds, dunning actions.
• Dunning Work Queue: accounts needing support intervention.
• Feature Access View: entitlements consumed by the product runtime.