Vendor Validation & Authentication: Know Who You’re Paying Before the Payment Goes Out
Are You Paying Who You Think You’re Paying?
There’s a question buried in every vendor payment your organization sends: are you actually paying who you think you’re paying?
For most finance and procurement teams, the honest answer is “probably.” They onboarded the vendor, they have the banking details on file, and nobody has flagged anything unusual. But that’s not authentication. That’s assumption.
Vendor validation is the process of confirming vendor identity at the points in your workflow where it matters most: before a new vendor is added to your financial system, when payment details change, and at any point where the authenticity of a request can’t be taken for granted. It’s not a one-time checkbox. It’s a control that runs at every high-risk moment in the vendor relationship.
This page covers what vendor validation actually requires, where most organizations have gaps, and why identity authentication has become one of the highest-leverage controls in accounts payable.
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What Vendor Validation Means (And What It Doesn’t)
Vendor validation gets conflated with vendor onboarding, and they’re not the same thing.
Onboarding is the process of collecting information from a vendor: their legal name, tax ID, banking details, and contact information. Validation is the process of confirming that the information they provided is accurate, that the business identity they’re claiming is real, and that the bank account they’ve submitted actually belongs to them.
You can have a thorough onboarding process and still have a weak validation posture. Collecting information isn’t authenticating it.
Genuine vendor identity authentication means checking submitted data against authoritative external sources — not just accepting what the vendor provided and filing it. It means confirming that the tax ID matches IRS records,, that the bank account belongs to the entity in question, and that it doesn’t appear on sanctions lists.. That’s vendor validation.
Why “We Called Them” Isn’t Enough
The most common vendor authentication practice in AP departments is also the most easily exploited: calling the vendor to confirm their banking details.
On its surface, this seems reasonable. You’re going out of band, you’re making a human connection, you’re not just accepting an email. The problem is in how the callback is typically executed.
If your AP team calls the phone number provided in the update request — the number in the email, or the number the vendor provided when they submitted the change — that number may be controlled by the same fraudster who initiated the request. Business email compromise schemes frequently include a fake callback number, specifically because they anticipate this response.
Effective vendor validation requires calling a number you already have on file for the vendor, sourced before this interaction, and authenticated through your onboarding process. That’s out-of-band authentication. A callback to a number provided in the suspicious request is not.
This is a subtle distinction. It’s also a critical one.
It’s worth going a step further here: many phone systems now route voicemail straight to email, so leaving a message isn’t the same as completing verification. If you call the number on file and it goes to voicemail, that doesn’t count — you need to actually speak with a person before proceeding.
The Three Moments Where Vendor Validation Has to Happen
Vendor identity authentication isn’t a single event. It’s a continuous process with specific high-risk moments that demand heightened controls.
At onboarding. This is the most foundational point. Before a vendor is added to your financial system, their identity needs to be confirmed against authoritative data sources. Tax ID authenticated against IRS records. Bank account ownership validated. creened against sanctions lists., Every vendor should go through this process before they receive a single payment.
When payment details change. Banking detail changes are the highest-risk event in an ongoing vendor relationship. Fraudsters know this. BEC schemes specifically target this moment because a successful payment redirect can yield a large, immediate return. Any request to change account numbers should trigger a full re-authentication workflow, not just an email acknowledgment.
At periodic intervals. Vendor identity doesn’t stay static. Businesses change, bank accounts change, and the threat landscape evolves. Ongoing vendor validation — periodic screening, re-confirmation of key identity elements, monitoring for unusual activity — is the difference between a program that catches emerging risk and one that only detects it after a loss.
What Strong Vendor Validation Actually Looks Like
Strong vendor identity authentication isn’t a single control. It’s a layered set of checks that, together, make impersonation and payment redirection significantly harder to execute.
Tax ID. Confirming that the entity claiming to be your vendor matches the tax information on file. This is key for many automated services confirming bank account ownership.
Bank account ownership validation. Confirming that the bank account submitted belongs to the vendor entity in question. Not just that the account is real — that it belongs to them. This requires more than a VOID check or a self-certification from the vendor.
Out-of-band authentication for changes. Any change to banking details should be authenticated through a channel independent of the change request itself. Phone callback on a pre-verified number. Not an email confirmation, and ot the number in the request.
Sanctions and watchlist screening. Automated screening against key sanctions lists such at OFAC and Sam.gov at onboarding and on an ongoing basis. Manual screening is inconsistently applied, risky, and difficult to document at scale.
A documented authentication audit trail. You need to be able to demonstrate, at any point, what authentication steps were taken for a given vendor, when they were taken, and what they returned. This matters for audits. It also matters in the event of a dispute or insurance investigation.
The Cost of Skipping This Step
Weak vendor validation creates two categories of risk, and they compound each other.
The first is direct financial exposure. Payment fraud that exploits a gap in your identity authentication process is difficult to recover from once the funds have moved. ACH reversals have a narrow window. The practical expectation in most cases is that the money is gone.
The second is audit and compliance exposure. Regulators and auditors increasingly scrutinize vendor identity controls, particularly for organizations handling sensitive payments, federal contracts, or payments to foreign entities. If you can’t demonstrate that you authenticated vendor identities before paying them, that’s a finding. It’s the kind of finding that triggers remediation requirements and follow-up audits.
The two risks often surface simultaneously. An incident that triggers a fraud investigation frequently also triggers an audit of the controls that should have prevented it.
Why Vendor Validation Fails in Practice
Most organizations understand the importance of vendor identity authentication in principle. The breakdown is almost always operational.
Manual validation processes are inconsistent. When the AP team is running behind, shortcuts get taken. When a request comes in from a known vendor, the assumption is that it’s legitimate. When the process depends on individual judgment rather than a documented workflow, the control degrades over time.
The other common failure point is scope creep in the opposite direction: organizations apply validation controls to new vendors but not to changes for existing ones. Fraudsters know this. Banking change requests targeting established vendor relationships are a known and frequently exploited pattern, precisely because existing vendors tend to receive less scrutiny than new ones.
How PaymentWorks Handles Vendor Validation
PaymentWorks is a vendor identity platform that centralizes and automates the vendor authentication process, removing the reliance on manual steps and individual judgment calls.
When a vendor is onboarded through PaymentWorks, they’re authenticated against 1st-and-3rd-party data sources before any information is entered into your financial system. Vendor ACH payments are guaranteed. Sanctions screening runs automatically, and continuously. And the entire process generates a documented, Nacha compliant audit trail.
When an existing vendor’s banking change request comes in, it routes through the same authentication workflow, not a freeform email exchange. The vendor proves they’re who they say they are before the change takes effect.
The result is a vendor identity authentication process that’s consistent, documented, and doesn’t depend on your AP team being CSI level forensic detectives.
Take the Next Step
If you’re not confident that your current vendor validation process is running consistently at every high-risk moment — onboarding, banking changes, and ongoing — that’s the place to start.
The question worth asking isn’t “do we have a validation process?” Most organizations do. The question is: “Does it run every time, for every vendor, at every moment it needs to?”