What is Straight-Through Processing?
Straight-through processing (STP) is the fully automated end-to-end processing of a payment or transaction from initiation to final settlement without any manual intervention.
Definition
Straight-through processing (STP) is the fully automated processing of a transaction — such as a payment, order, or trade — from initiation through to final settlement, without any manual intervention at any step in the process. STP is measured as a rate: STP Rate = (Transactions processed automatically / Total transactions) × 100. A 95% STP rate means 95 out of 100 transactions process completely automatically; 5 require some form of manual review or intervention. STP originated in financial markets (equities, derivatives, foreign exchange) but is now widely used in payment processing, accounts payable, and accounts receivable contexts.
How STP Works in Payment Processing
In the context of B2B payments, STP means a payment initiated by a buyer flows automatically through every step: validation of payment details, compliance and fraud screening, routing through the payment network (ACH, RTP, SWIFT), matching to the correct vendor invoice (cash application), and posting to both parties' bank accounts — all without a human touching the transaction. For this to work, the buyer's accounts payable system must generate payment instructions in a standardized format (typically ISO 20022), the payment network must be able to read and process these instructions automatically, and the vendor's accounts receivable system must be able to match the incoming payment to the correct open invoice automatically.
Benefits of High STP Rates
High STP rates (95%+) deliver significant operational and financial benefits. Cost reduction: each manual transaction in accounts payable or accounts receivable costs $5–$20 in labor. Automating 1,000 transactions per month at a 95% STP rate saves $950–$3,800 per month in manual processing costs. Speed: STP transactions settle in minutes or hours, while manual processing adds days. Error reduction: manual data entry errors cause failed payments, misapplied cash, and duplicate transactions — STP eliminates these. Scalability: a high STP operation can handle 10x the volume without proportionally increasing staff. Improved vendor relationships: fast, accurate payments strengthen supplier relationships and may earn you early payment discounts.
How to Improve Your STP Rate
Improving STP requires addressing the specific failure points in your payment process. For AP (outgoing payments): use standardized payment file formats (ISO 20022), validate vendor banking details before sending, automate payment approval workflows so payments are released without manual steps, and integrate your ERP with your payment processor to eliminate re-keying. For AR (incoming payments): require clients to include invoice numbers on all payments, use a payment portal where clients submit payment with remittance data, automate cash application using AI to match incoming payments to open invoices, and send invoices electronically so payment data is already in the system when payment arrives.
STP in Accounts Receivable: Cash Application
Cash application — matching incoming customer payments to open invoices — is the most common STP bottleneck in AR. When a customer pays without a proper invoice reference, the payment cannot be automatically matched and must be manually identified by an AR clerk. This is a major driver of low STP rates in AR. AI-powered cash application tools now achieve 80–95% straight-through matching rates by using machine learning to analyze payment metadata, historical patterns, and partial invoice references to automatically match previously unmatched payments. Eonebill's payment reconciliation features help ensure that invoice references are clear and consistent, making cash application as automatic as possible.