Visa and Mastercard offer reduced interchange rates on commercial cards (corporate, purchasing, business cards) when the merchant sends additional transaction data. Level 2 requires tax amount and customer/PO number. Level 3 requires line-item detail (item description, quantity, unit cost, tax per line). The savings are substantial: 50–100 basis points on a typical commercial card transaction.
For B2B businesses (contractors, HVAC, law firms, accountants, consultants), failing to send Level 2/3 data is one of the largest hidden costs. A $5,000 invoice processed without Level 2/3 might cost $145; the same transaction with full Level 3 data could cost $75–$95.
Most processors require you to enable Level 2/3 in their gateway settings. Authorize.net, Stripe, Braintree, and most modern interchange-plus processors support it — but it's rarely enabled by default.