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How to prevent internal fraud at your bank or credit union

Terri Luttrell, CAMS-Audit, CFCS
March 11, 2025
0 min read
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How to prevent internal fraud at your bank or credit union 

Of the many fraud risks banks and credit unions face, one of the most costly comes from within the institution itself. Employees in positions of trust may manipulate accounts, conceal information, or abuse their authority for personal gain. Learn how to prevent internal fraud in banks and credit unions. 

 Key topics covered in this post: 

 

What is internal fraud?

Internal fraud occurs when an employee deliberately misuses their position of trust to commit financial misconduct, either for personal gain or to cause losses to the institution. Unlike external fraud that originates outside the organization, internal fraud is perpetrated by individuals who have legitimate access to accounts, systems, and sensitive data. This can include falsifying financial records, misappropriating funds, or manipulating transactions to conceal illicit activities.  

In a 2024 report, the Association of Certified Fraud Examiners (ACFE) found that insider fraud represents a significant risk to every organization's operations. ACFE reported that 5% of an organization’s revenue is lost to internal fraud each year, with an estimated $3.1 billion in total losses. Banking and financial services accounted for the largest share of internal fraud cases examined by ACFE. 

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Understanding internal fraud 

According to Federal Reserve data, a typical bank can process millions of transactions per day, with estimates ranging from tens of millions for large institutions to a few thousand for smaller branches. Because of this heavy transaction volume, internal fraud can go undetected for long periods. Understanding the various forms of internal fraud and implementing proactive measures is critical to protecting an institution’s financial health and reputation. 

Some of the more common types of internal fraud include: 

  • Account manipulation: A bank employee manipulates charges, adjusts loan interest rates, or increases credit limits—directly impacting the institution’s profits for personal gain. 
  • Transaction reversals: Tellers accept deposits from a customer and cancel legitimate transactions to reverse the deposit and steal funds.  
  • Account takeovers: An employee gains access to a dormant account and carries out unauthorized transactions. 
  • Loan application fraud: Employees falsify loan approvals using stolen customer identification and use the funds without intending to pay back the loan. 
  • General ledger fraud: An employee sets up a fake vendor account, generates fraudulent invoices, and then processes payments through the bank’s general ledger to divert funds for personal gain. 
  • Internal collusion: Employees work together to override controls. Multi-person fraud is difficult to detect as it might involve important stakeholders from different departments covering up for each other.  
  • Data theft: Unauthorized access and misuse of sensitive customer information. 
  • IT back-end changes: An employee makes unauthorized system modifications that facilitate fraud, or grants access to a non-IT employee who can then approve a fraudulent transaction. 
  • Credit abuse: An employee manipulates credit lines for unauthorized use, perhaps leading to the bank lending more than the borrower can pay. 

What are the warning signs of internal fraud?

Fraudulent activity often leaves subtle clues before becoming a significant issue. Financial institutions should monitor for the following warning signs: 

  • Unusual activity in dormant accounts 
  • Excessive customer complaints about incorrect balances or missing funds 
  • Employees who avoid taking time off, possibly to conceal misconduct 
  • Unexplained increases in expenses or unusual invoice patterns 
  • Bypassing of validation controls in financial systems 
  • Employees under financial pressure or with unexplained lifestyle changes 

Preventing internal fraud in banks and credit unions 

Proactive fraud prevention requires a combination of strong leadership, transparent policies, and embedded controls. Here are key strategies to mitigate internal fraud risks: 

  1. Set the right tone at the top

Leadership should communicate a strong culture of compliance and a zero-tolerance policy for fraud. When executives and managers uphold ethical standards, employees are more likely to follow suit. 

  1. Establish a clear company code of conduct

A well-documented code of conduct outlines expectations for ethical behavior, including the consequences of fraudulent activities. Employees should receive regular training on fraud risks and reporting procedures. 

  1. Strengthen procedural controls

Financial institutions must enforce strict approval authority requirements and segregate duties to reduce opportunities for fraud. Employees handling financial transactions should not have authority over both the initiation and approval processes. 

  1. Implement embedded controls

Automated fraud detection systems can flag unusual transaction patterns and enforce validation protocols. Embedded controls within IT systems help prevent unauthorized modifications or data access. 

  1. Enforce accounting system access controls

Restricting access to financial systems based on job roles minimizes the risk of unauthorized transactions. Regular audits ensure compliance and identify potential vulnerabilities. 

  1. Require mandatory vacation and job rotation

Employees engaged in fraudulent activities often avoid taking time off. Enforcing mandatory vacations and periodically rotating job responsibilities can expose irregularities. 

 

The role of technology in detecting and preventing internal fraud 

Technology plays a vital role in helping financial institutions identify and prevent internal fraud. Automated fraud detection monitoring systems can track transaction patterns, flagging unusual activity that may indicate fraudulent behavior. Role-based access controls ensure employees can only access the data and systems necessary for their jobs, reducing opportunities for misconduct. Audit logs provide a clear record of system changes and approvals, making it easier to spot unauthorized actions. Behavioral analytics can also help detect red flags, such as employees frequently overriding controls or accessing sensitive information outside of regular business hours. By leveraging these tools alongside strong internal policies, financial institutions can stay ahead of internal fraud risks and protect their reputation. 

 

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FAQs

What is internal fraud at a bank or credit union?

Internal fraud occurs when an employee deliberately misuses legitimate access, authority, or a trusted position to commit financial misconduct for personal gain or to harm the institution. It can involve falsifying records, diverting funds, manipulating transactions, or misusing customer data and differs from external fraud because the perpetrator operates from inside the organization.

What are the most common types of internal fraud in financial institutions?

Common types of internal fraud include account manipulation, transaction reversals, dormant-account takeovers, fraudulent loan approvals, fake-vendor schemes, employee collusion, data theft, unauthorized system changes, and credit abuse. These schemes can be difficult to identify because employees may understand internal workflows and possess valid access to accounts, systems, or approval processes.

What warning signs can indicate internal fraud at a financial institution?

Potential warning signs include unusual dormant-account activity, recurring customer complaints about balances or missing funds, unexplained expenses, abnormal invoice patterns, and repeated control overrides. Other indicators may include employees who resist taking leave, access sensitive information outside normal hours, face financial pressure, or display unexplained lifestyle changes.

How can banks and credit unions prevent internal fraud?

Banks and credit unions can prevent internal fraud by combining ethical leadership with clear policies, employee training, segregation of duties, restricted system access, and routine audits. Embedded validation controls and automated monitoring should identify unusual transactions or unauthorized changes, while mandatory vacations and job rotation can expose activity that depends on one employee maintaining continuous control.

How does technology detect and prevent internal fraud in banks?

Technology helps detect internal fraud by monitoring transaction patterns, limiting system access according to job responsibilities, and preserving audit logs of changes and approvals. Behavioral analytics can flag repeated overrides, unusual access to sensitive information, or activity outside normal working hours, giving fraud and audit teams specific events to investigate.

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About the Author

Terri Luttrell, CAMS-Audit, CFCS

Compliance and Engagement Director
Abrigo
Terri Luttrell is a seasoned AML professional and former director and AML/OFAC officer with over 20 years in the banking industry, working both in medium and large community and commercial banks ranging from $2 billion to $330 billion in asset size.

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About Abrigo

Abrigo enables U.S. financial institutions to support their communities through technology that fights financial crime, grows loans and deposits, and optimizes risk. Abrigo's platform centralizes the institution's data, creates a digital user experience, ensures compliance, and delivers efficiency for scale and profitable growth.

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