billing-automation

SKILL.md

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.