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name: billing-automation description: Build automated billing systems for recurring payments, invoicing, subscription lifecycle, and dunning management. Use when implementing subscription billing, automating invoicing, or managing recurring payment systems.

Billing Automation

Master automated billing systems including recurring billing, invoice generation, dunning management, proration, and tax calculation.

When to Use This Skill

• Implementing SaaS subscription billing
• Automating invoice generation and delivery
• Managing failed payment recovery (dunning)
• Calculating prorated charges for plan changes
• Handling sales tax, VAT, and GST
• Processing usage-based billing
• Managing billing cycles and renewals

Core Concepts

1. Billing Cycles

Common Intervals:

• Monthly (most common for SaaS)
• Annual (discounted long-term)
• Quarterly
• Weekly
• Custom (usage-based, per-seat)

2. Subscription States

trial → active → past_due → canceled
              → paused → resumed

3. Dunning Management

Automated process to recover failed payments through:

• Retry schedules
• Customer notifications
• Grace periods
• Account restrictions

4. Proration

Adjusting charges when:

• Upgrading/downgrading mid-cycle
• Adding/removing seats
• Changing billing frequency

Quick Start

from billing import BillingEngine, Subscription

# Initialize billing engine
billing = BillingEngine()

# Create subscription
subscription = billing.create_subscription(
    customer_id="cus_123",
    plan_id="plan_pro_monthly",
    billing_cycle_anchor=datetime.now(),
    trial_days=14
)

# Process billing cycle
billing.process_billing_cycle(subscription.id)

Detailed patterns and worked examples

Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.