Accounts Payable (AP) is a vital function in every finance team — covering invoice processing, PO matching, approvals, and timely payments. But when errors occur, such as duplicate payments or missing POs, the result is financial loss, strained supplier relationships, and compliance risks.
This article explores the 11 most common AP errors in invoice processing, why they happen, and how to resolve them with automation, real-time visibility, and fraud prevention.
Why AP Errors Are a Big Deal
AP errors aren’t minor — they lead to lost discounts, payment penalties, and strained supplier trust. Without audit trails, compliance risks grow. Automation tools like Fraud Risk Detection help spot issues early, enforce controls, and safeguard margins.
Common Mistakes in AP Processing (and How to Avoid Them)
From delayed payments to invoice fraud, AP errors can steadily erode your margins. Below are 11 of the most common — and costly — mistakes finance teams encounter, along with practical solutions using smart automation and tighter controls.
1. Duplicate Invoice Payments
Paying the same invoice more than once is a costly and surprisingly common error. It often occurs when invoice copies are submitted via multiple channels, or when manual checks are rushed.
Fix: Medius Copilot automatically flags duplicates and verifies invoice metadata before payment — preventing duplicate payouts and safeguarding your margins.
2. Missing Purchase Orders (POs)
Invoices without corresponding POs leave room for unauthorised or unverified payments. Without a PO, there’s no audit trail for validation.
Fix: A three-way match system (PO, invoice, and receipt), powered by automation, ensures every invoice is accurately verified before approval.
3. Late Approvals & Missed Discounts
Manual invoice routing often causes delays — potentially missing early payment discounts that could benefit cash flow.
Fix: Automated approval workflows assign routing based on predefined rules and roles, enabling timely approvals and helping maximise available discounts.
4. Invoice Fraud
Fraudulent invoices from fake suppliers or manipulated data can slip through during manual checks, especially when teams are overburdened.
Fix: AP Flow’s Fraud Risk Detection tool leverages AI to flag anomalies and send real-time alerts before payments are processed.
👉 Discover Fraud Risk Detection
5. Incomplete or Outdated Vendor Information
Bank account mismatches or outdated tax IDs can result in failed payments or regulatory issues.
Fix: With AP Flow’s Supplier Conversations module, supplier data is centrally managed and verified, helping reduce costly errors.
👉 Learn about Supplier Conversations
6. Manual Data Entry Errors
Entering invoice details manually is prone to errors — incorrect currencies, quantities, or prices can disrupt financial planning.
Fix: OCR and AI-powered invoice capture via Medius Copilot accurately reads and processes data, significantly reducing human error.
7. Unmatched Invoices and Receipts
When procurement, receiving, and finance teams operate in silos, it’s easy to lose track of what has been ordered and received.
Fix: Automating the 3-way match (PO, receipt, and invoice) bridges the gap and ensures payments are only made when all data aligns.
8. Approvals via Email or Excel
Using email chains or spreadsheets for invoice approvals is risky — lacking visibility, control, and a proper audit trail.
Fix: Procure-to-pay systems route approvals based on roles and value thresholds, ensuring consistency and traceability.
9. Delayed Supplier Communication
A lack of timely updates on invoice or payment status can lead to duplicate shipments, strained relationships, or delivery setbacks.
Fix: AP Flow’s Supplier Conversations automates updates, milestones, and reminders — keeping all stakeholders aligned.
10. Shadow Spend
When teams make purchases outside of approved systems, it results in reduced visibility, overspending, and a lack of policy compliance.
Fix: Sourcing automation ensures all procurement follows approved protocols, keeping spend controlled and within policy boundaries.
11. No Spend Visibility
Without real-time insight into how much is being spent, where, and why — you’re forced to make reactive decisions.
Fix: Medius Copilot offers predictive dashboards and live alerts, enabling you to manage costs proactively and prevent overspending.
How Finance Teams Can Fix AP Errors In Invoice Processing For Good
Solving accounts payable issues goes beyond error reduction — it’s about building a smarter, more resilient finance function. With automation, teams gain real-time visibility, streamline sourcing, and detect fraud early.
Tools like Medius Copilot and AP Flow help shift from reactive fixes to proactive control, ensuring long-term efficiency and profitability. Now is the time to digitise your AP and safeguard your margins
✅ Ready to Eliminate Errors and Protect Margins?
Book a free audit with our experts and uncover hidden risks within your AP workflows. Let’s transform your invoice process together.