2026 Nacha Rule Change: Proactive Fraud Monitoring of ACH Now a Requirement

Nacha’s 2026 rules turn ACH into a fully monitored fraud rail. From March 20, 2026, banks that send or receive these payments must be able to spot both clearly unauthorized transfers and those sent under False Pretenses.

Key Takeaways

• Existing Outseer customers can immediately meet the new Nacha monitoring requirements by adding ACH payments into your existing solution.
• ODFIs and RDFIs are all being asked to implement risk-based monitoring for transactions to target scams.
• Phase 1 (March 2026) and Phase 2 (June 2026) are fast-approaching deadlines, and financial institutions are encouraged to act now.
• Unlike Reg E for debit-pull, these new rules don't shift liability for credit-push transactions.
• This change creates an obligation to govern, test, and update fraud policies annually.

2026 Nacha Rule Changes Timeline

The Nacha 2026 rule changes are one of the biggest shake ups to ACH in recent years. They turn fraud monitoring into an all-round obligation, not a narrow focus on unauthorized debits. They arrive as scams have surged, creating a compound threat surface for banks: more unauthorized fraud and a sharp rise in “authorized” scam losses.

Phase 1: March 20, 2026: Larger senders and receivers must start risk-based monitoring for both unauthorized and “false pretenses” payments.

Phase 2: June 2026: All remaining banks that send or receive these payments are expected to have the same monitoring in place.

Ongoing: From 2026: Review and update your ACH fraud monitoring at least annually.

Banks and credit unions are expected to act fast to monitor ACH the way they already watch cards and instant payments: looking for any payment that should not have gone out or come in, whether the customer technically authorized it or not.

For companies already using the Outseer Fraud Manager platform, you already have a solution that enables you to become compliant with Nacha’s new fraud detection rules.

Dive deeper: What changes for banks in 2026

1. Universal, risk-based monitoring

Monitoring extends from specific online debits (for example, WEB) to the full ACH book. Nacha expects sending and receiving banks to have processes “reasonably intended” to identify fraudulent entries using a risk-based approach.

2. “False Pretenses” becomes a defined fraud category

False Pretenses is now a defined Nacha fraud category. It covers payments where the customer appears to authorize the transaction, but only after someone has misrepresented who they are, their authority to act, or which account should receive the funds.

• Consumer scams where a criminal poses as the bank, a government agency, or a trusted company and coaches the customer through sending an ACH payment.
• Impersonation-driven payment changes such as fake “security” or “HR” messages prompting customers to update payment or account details.
• Payroll redirection fraud where individuals are tricked into changing salary or benefit instructions to an account controlled by a criminal.

These payments usually pass standard authentication and device checks. The reliable signal is deviation from the customer’s historical behavioral and transactional patterns, not a simple authorized versus unauthorized test.

3. ODFIs and originators: outbound fraud oversight

ODFIs must monitor all outgoing ACH payments for both unauthorized activity and False Pretenses. They also need to clearly spell out fraud monitoring expectations in their agreements, risk assessments, and oversight of business originators and third-party senders.

4. RDFIs: inbound credits and mule activity

For the first time, RDFIs must monitor incoming credits, starting with those receiving at least 10 million entries in 2023, then all receivers. This additional risk evaluation of received credits plugs a big gap. Expected signals include:

• New or dormant accounts receiving high dollar or high velocity credits
• Multiple unrelated payroll credits to a single consumer account
• Corporate-coded credits flowing into consumer accounts
• Abrupt shifts in account usage that indicate mule activity

RDFIs are expected to return suspect entries or coordinate with the ODFI before funds exit the system.

5. Continuous program review

All covered participants must review and update fraud monitoring at least annually in light of evolving scam patterns. This creates a recurring exam and audit surface.

Why it matters now: risk, liability, and exam pressure

If you still look at ACH fraud mainly through return rates, you’re exposed in three four ways:

1. Scam losses for your customers
   Scam-driven ACH credits and debits slip through traditional controls. Consumer and SMB scams, payroll diversions, and vendor impersonation can scale quickly without contextual monitoring.
2. Regulatory and Nacha enforcement risk
   Failure to implement documented, risk-based monitoring is a direct rules violation. That opens the door to Nacha fines, corrective action, closer monitoring, and, in persistent cases, network-level penalties or even suspension for non-compliant originators.
3. Exam findings and safety and soundness concerns
   Examiners will treat weak ACH fraud programs as evidence of broader deficiencies in operational risk, consumer protection, and governance. That does not change legal liability allocations under Reg E and UCC, but it changes how your controls and loss handling will be viewed.
4. Reputational Risk
   ‍When customers lose money to scams and Nacha finds your fraud controls lacking, reputational damage is serious: regulators question your program, peers see higher risk, and customers doubt your ability to protect their accounts.

Where defenses fall short today

Most institutions have invested heavily in strong authentication and device binding. Those controls are effective against credential theft and some account takeover scenarios. They do not address systemic blind spots that Nacha is now codifying:

• Authorized under coaching: A fraudster walks the customer through a “bank security process” over the phone, screen share, or chat, while the customer logs in and initiates ACH payments that look technically normal.
• BEC and payment redirection: Corporate or SMB customers change beneficiary details in line with a familiar invoicing cadence. Timing, channel, and approval flows all appear legitimate.
• Mule network velocity: Consumer or small business accounts receive multiple inbound credits from unrelated sources and move them out quickly via ATM, P2P, or other rails.

Static rules based only on transaction amounts and speed miss how the customer is actually interacting. They do not see hesitation, unusual on-screen behavior, or patterns that look strange across channels. Most ACH systems were built to move payments quickly, not to combine signals and spot fraud.

What a Nacha-ready ACH fraud program looks like

For financial institutions, a credible Nacha-aligned program has five layers. The first step is simply to include ACH payments in your existing fraud monitoring through the Outseer platform. The additional layers below show future steps banks can take to strengthen fraud and scam prevention on the ACH rail.

1. Risk-based coverage across roles and flows

• ODFIs: Must monitor all originated ACH entries for unauthorized or False Pretenses risk and enforce fraud-monitoring expectations with originators and third-party senders. Their responsibility extends to the payment processors and businesses sending money (eg. payroll companies).
• RDFIs: With simpler requirements than ODFIs, they must monitor incoming credits, starting with large-volume receivers in Phase 1, then all receivers.
• Corporate entities and TPS/TPSPs: Third-party service providers and senders must support ODFI programs and demonstrate risk-based monitoring.

The key is tiered monitoring so that higher-risk payments get deeper checks and stronger controls, without full pre-processing review on every payment.

2. Behavioral and device intelligence

Nacha’s focus on False Pretenses pushes institutions toward detecting human manipulation, not just system misuse. That means:

• Measuring interaction continuity, unusual navigation, and hesitation spikes
• Detecting copy/paste or scripted input that indicates remote coaching or scripting
• Assessing device trust, IP profile, and geolocation anomalies relative to the account
• Watching for session instability that suggests remote access tools

These signals must feed the same risk engine that evaluates amount, timing, counterparties, and ACH-specific metadata.

3. ACH anomaly modeling and mule detection

Banks need targeted models for ACH-specific risk patterns, for example:

• First-time beneficiaries and changes to beneficiary details, weighted by sector and historical relationship
• Abrupt changes in pay file composition (new “employees,” inflated payroll, diverted vendor payments)
• Anomalous Company Entry Descriptions or mismatches between SEC code and account type
• Mule network velocity signatures across inbound credits, P2P outflows, and ATM withdrawals

Models should score individual entries and sessions, plus accounts and relationships over time, to surface emerging mule hubs and compromised originators. These models go beyond the minimum Nacha requirement, but they materially improve early detection of scams and mule activity.

4. Risk-based orchestration and workflow

Nacha expects institutions to do more than score transactions; they must act on suspicion using documented procedures. Effective programs:

• Route high-risk ACH entries into different paths: step-up, hold, manual review, or deny
• Define clear contact and challenge scripts for ODFIs calling originators and RDFIs contacting account holders or counterparties
• Integrate with the ACH Contact Registry for rapid bank-to-bank coordination on suspect credits and recovery attempts
• Align ACH monitoring with BSA/AML case management for shared mule, scam, and network intelligence

Case management must preserve full evidence: session details, risk scores, model explanations, analyst decisions, and final outcomes for audit and Nacha inquiries.

5. Governance, testing, and documentation

To withstand Nacha and regulatory scrutiny, banks should be able to show:

• A written ACH fraud monitoring program that distinguishes ODFI and RDFI responsibilities
• Periodic model performance review and recalibration against new scam and BEC patterns
• Regular training for fraud ops, treasury, and frontline teams on False Pretenses scenarios
• Annual program reviews with documented changes based on loss experience and industry data

If you cannot hand an examiner a coherent narrative of “how we detect scams in ACH, how we tune it, and what has changed in the last year,” you have a governance problem, not just a tooling gap.

How Outseer helps you meet the Nacha 2026 obligations

For banks and credit unions already using Outseer, most of the required capabilities exist today. You can achieve Nacha-aligned ACH monitoring by feeding ACH events into your existing Outseer deployment, then phasing in more advanced use cases over time.

ACH anomaly detection

Leverage a comprehensive transactional risk platform and risk-based scoring. Outseer risk models can be extended to ACH with features such as first-time payee risk scoring and detection of unusual timings or distribution amounts.

Risk-based orchestration and evidence

Outseer’s policy engine lets you route ACH sessions and entries into differentiated paths based on risk:

• Passive allow for low-risk repeat payments
• Step-up challenges, callbacks, or in-session warnings for medium-risk behavior
• Holds, denials, or enhanced review for high-risk entries and accounts

Outseer helps you maintain a full record of risk scores, contributing factors, analyst findings, and final decisions so you can substantiate your Nacha compliance, exam responses, and internal reviews.

Device and session intelligence

Outseer’s device recognition and telemetry highlight:

• New or rare devices initiating high-risk ACH activity
• IP and geolocation shifts inconsistent with account history
• Session anomalies associated with remote access tools and scripted controls

Behavioral intelligence for False Pretenses

For banks looking to go further in detecting high-risk ACH activity, Outseer’s behavioral biometics captures human behavioral micro-patterns. These include hesitation, unusual navigation paths, repeated field edits, copy/paste behavior in critical fields, and interaction continuity. These are strong indicators of scam coaching, remote access, or manipulation, even when the login and device appear normal.

Applying those signals to ACH initiation and beneficiary maintenance gives you concrete evidence that a transaction originated under false pretenses, satisfying Nacha’s expectation to monitor beyond “unauthorized” entries.

Closing

The 2026 Nacha rules make it clear that monitoring both authorized and unauthorized fraud across all payment types is now a core banking obligation.

If you already use Outseer, you can achieve compliance quickly within your existing technology stack. We can work with you to bring ACH into the fraud platform and policies, then add more advanced signals over time as you need them.