A SKU (Stock Keeping Unit) is a unique code that identifies a specific product or service offering. In SaaS, SKUs are assigned to each plan, add-on, and one-time charge, enabling accurate tracking in billing systems, revenue reporting, and financial reconciliation.

Example: A SaaS company assigns SKU-001 to its Starter plan, SKU-002 to its Pro plan, SKU-003 to its API add-on, and SKU-004 to a one-time onboarding fee. Each line item on a customer invoice references the corresponding SKU for accurate reporting.