IRS Audit Triggers — What Increases Your Audit Risk

Understanding IRS Audit Selection and Examination Authority

The Internal Revenue Service (IRS) derives its primary authority to examine tax returns from Internal Revenue Code (IRC) §7602, which empowers the Secretary to "examine any books, papers, records, or other data which may be relevant or material" to determine the correctness of any return. This authority is broad, and while the overall audit rate for individual returns remains below 1%, the strategic application of enforcement resources means that certain taxpayers face significantly higher scrutiny.

In 2026, the IRS's examination landscape has been fundamentally altered by the One, Big, Beautiful Bill (OBBBA) and the continued implementation of the Inflation Reduction Act. These legislative frameworks have provided the IRS with unprecedented funding to modernize its Discriminant Information Function (DIF) scoring system and increase audit coverage for high-income individuals, complex pass-through entities, and large corporations.

Deep Dive: IRC §7602 and the Scope of IRS Examination Powers

To truly understand audit risk, one must understand the statutory foundation of the IRS's power. Internal Revenue Code §7602 is the "bedrock" of tax enforcement. It provides that for the purpose of ascertaining the correctness of any return, making a return where none has been made, or determining the liability of any person for any internal revenue tax, the Secretary is authorized to examine any books, papers, records, or other data which may be relevant or material to such inquiry.

The Supreme Court has consistently upheld the breadth of this power. In United States v. Powell, 379 U.S. 48 (1964), the Court established that the IRS does not need "probable cause" to initiate an investigation. Instead, the IRS must show that the investigation will be conducted pursuant to a legitimate purpose, that the inquiry may be relevant to the purpose, that the information sought is not already within the Commissioner's possession, and that the administrative steps required by the Code have been followed.

Practitioners should note that §7602(c) requires the IRS to provide "reasonable notice in advance" to the taxpayer before contacting third parties (such as banks, vendors, or clients) regarding the determination or collection of the taxpayer's tax liability. This is a critical procedural safeguard that practitioners should monitor closely during an examination.

Key Rules and Thresholds for 2026

For the 2026 tax year, practitioners must be aware of the following inflation-adjusted figures and statutory thresholds that influence audit selection and tax liability:

• Standard Deduction (MFJ): $32,200 (as adjusted by OBBBA)
• Standard Deduction (Single): $16,100
• Social Security Wage Base: $176,100
• Bonus Depreciation: 60% (under the TCJA phase-down schedule)
• QBI Deduction: 23% (as enhanced by OBBBA §199A amendments)
• 401(k) Elective Deferral Limit: $24,500 (plus $8,000 catch-up for age 50+)
• IRA Contribution Limit: $7,500 (plus $1,100 catch-up for age 50+)

Understanding these figures is critical because the IRS's automated systems are programmed to flag returns that claim deductions or credits in excess of these statutory limits or that show unusual ratios relative to reported income.

The Role of the National Research Program (NRP) in Audit Selection

While most audits are triggered by high DIF scores, a small percentage of taxpayers are selected for the National Research Program (NRP). These are often referred to as "audits from hell" because they are not limited to specific items. Instead, the IRS examines every single line of the return to gather data for updating its DIF algorithms.

The NRP is essential for the IRS to maintain the accuracy of its automated selection systems. By conducting these comprehensive examinations on a representative sample of the taxpayer population, the IRS can identify new trends in non-compliance and adjust its scoring models accordingly. For practitioners, an NRP audit requires a different defense strategy: rather than focusing on a few "red flags," the practitioner must be prepared to substantiate every entry on the return, from filing status to miscellaneous credits.

Practitioner Implementation Guide: Managing Audit Risk

Effective audit risk management requires a proactive, multi-layered approach that begins long before a return is filed. Practitioners must implement rigorous internal controls and client education protocols to ensure that every position taken on a tax return is supported by substantial authority and documented with contemporaneous records.

Real Numbers Example: The Impact of Audit Triggers on a High-Income Professional

Consider the case of Dr. Jane Smith, a self-employed consultant with a gross income of $850,000 in 2026. Her return includes several high-risk items that could trigger a DIF score spike.

Audit Triggers for High-Net-Worth Individuals (HNWI) in 2026

In 2026, the IRS has established a dedicated Global High Wealth Industry Group (often called the "Wealth Squad") within the Large Business and International (LB&I) division. This group focuses on taxpayers with assets or income exceeding $10 million. The audit triggers for this group are significantly more complex than those for the general population.

• Tiered Partnership Structures: Using multiple layers of partnerships (LLCs, LPs) to move income and deductions. The IRS uses sophisticated data analytics to "see through" these structures and identify potential basis shifting or disguised sales.
• Private Foundation Transactions: Self-dealing or excessive business holdings within a private foundation (IRC §4941, §4943). The IRS scrutinizes these to ensure the foundation is operating for charitable purposes rather than personal benefit.
• Offshore Assets and FBAR Compliance: Failure to file FinCEN Form 114 (FBAR) or Form 8938 for foreign financial assets. With the expansion of the Common Reporting Standard (CRS) and FATCA, the IRS receives more data than ever from foreign financial institutions.
• Family Office Expenses: Reclassifying personal expenses as business expenses within a family office structure. Following the Lender Management, LLC v. Commissioner case, the IRS is particularly focused on whether a family office's activities rise to the level of a "trade or business" under IRC §162.

The Impact of the One, Big, Beautiful Bill (OBBBA) on Enforcement

The One, Big, Beautiful Bill (OBBBA), enacted in late 2025, provided a massive infusion of capital specifically earmarked for "Enforcement and Operations Support." This funding has allowed the IRS to hire thousands of new revenue agents and specialized tax attorneys, many of whom are being deployed to the newly created Pass-Through Entity Compliance (PEC) unit.

The OBBBA also introduced new reporting requirements for "high-frequency" transactions in digital assets and increased the penalties for "willful" failure to disclose offshore accounts. For practitioners, the OBBBA means that the "audit lottery" is becoming a thing of the past. The IRS now has the resources to follow every lead and litigate complex tax positions that it might have previously settled for pennies on the dollar.

State Applicability and Residency Audit Triggers

While federal audits are a primary concern, state tax agencies—particularly in high-tax jurisdictions like California (FTB), New York (DTF), and New Jersey—have become increasingly aggressive. State audit triggers often differ from federal ones, with a heavy focus on residency and "nexus" issues.

Common Mistakes and "Low-Hanging Fruit" for IRS Auditors

Many audits are triggered by simple, avoidable errors that flag a return for further scrutiny. Practitioners should implement a "final review" checklist to catch these items before filing.

• Mismatched Information: Failing to report income from a 1099-K (Third Party Network Transactions) or 1099-B (Brokerage Sales). The IRS's Automated Underreporter (AUR) program catches these with nearly 100% accuracy.
• Rounding Numbers: Reporting expenses in perfect increments of $100 or $1,000 (e.g., $5,000 for supplies, $2,000 for travel). This suggests the numbers are estimated rather than based on actual records, a major red flag for the DIF algorithm.
• Excessive Losses: Reporting Schedule C losses for three or more consecutive years. Under IRC §183, the IRS may reclassify the activity as a "hobby," disallowing all losses in excess of income.
• Large Miscellaneous Deductions: While the TCJA suspended most miscellaneous itemized deductions, certain categories (like gambling losses under IRC §165(d)) remain. Large claims in these areas are frequently audited.
• Inconsistent Filing History: A sudden, dramatic change in income or deductions from one year to the next without a clear explanation (such as a business sale or disaster loss) will often trigger a manual review.

Detailed Analysis: IRC §274(d) and the "Strict Substantiation" Rule

One of the most common reasons for audit adjustments is the failure to meet the "strict substantiation" requirements of IRC §274(d). This section applies to travel, entertainment, and "listed property" (which includes passenger automobiles). Unlike other business expenses where the "Cohan Rule" (Cohan v. Commissioner, 39 F.2d 540 (2d Cir. 1930)) might allow for a reasonable estimate, §274(d) explicitly prohibits estimates.

To claim a deduction under §274(d), the taxpayer must substantiate by adequate records or by sufficient evidence corroborating the taxpayer's own statement: (1) the amount of the expense, (2) the time and place of the travel or use of the property, (3) the business purpose of the expense, and (4) the business relationship to the taxpayer of the persons entertained or using the property.

In 2026, the IRS has issued Revenue Procedure 2026-15, which clarifies that digital logs must be "contemporaneous," meaning they are recorded at or near the time of the expenditure. Logs created at the end of the year based on calendar entries are frequently disallowed upon examination.

The "Hobby Loss" Trap: IRC §183 and the Nine-Factor Test

For Schedule C filers and owners of pass-through entities, IRC §183 (Activities Not Engaged in for Profit) is a major audit trigger. If an activity is deemed a "hobby," deductions are generally limited to the amount of income produced by the activity, and losses cannot be used to offset other income.

The IRS uses a nine-factor test found in Treas. Reg. §1.183-2(b) to determine profit motive:

1. The manner in which the taxpayer carries on the activity (e.g., keeping business-like books and records).
2. The expertise of the taxpayer or their advisors.
3. The time and effort expended by the taxpayer in carrying on the activity.
4. The expectation that assets used in the activity may appreciate in value.
5. The success of the taxpayer in carrying on other similar or dissimilar activities.
6. The taxpayer's history of income or losses with respect to the activity.
7. The amount of occasional profits, if any, which are earned.
8. The financial status of the taxpayer (e.g., does the taxpayer have substantial income from other sources?).
9. Elements of personal pleasure or recreation.

Practitioners should advise clients to maintain a formal business plan and a separate business bank account to demonstrate a profit motive, even during loss years.

Audit Triggers in the Real Estate Sector: IRC §469 and §1031

Real estate investors face unique audit triggers, primarily related to the Passive Activity Loss (PAL) rules under IRC §469 and Like-Kind Exchanges under IRC §1031.

• Real Estate Professional Status (REPS): To deduct rental losses against non-passive income, a taxpayer must qualify as a "real estate professional" under IRC §469(c)(7). This requires performing more than 750 hours of service in real property trades or businesses and more than half of their total personal service hours in such businesses. The IRS frequently audits the "time logs" used to support REPS status.
• Material Participation: Even if a taxpayer is a real estate professional, they must "materially participate" in each specific rental activity (unless an election is made to group activities). The IRS scrutinizes the seven tests for material participation found in Treas. Reg. §1.469-5T(a).
• 1031 Exchange Identification: Failure to properly identify replacement property within the 45-day window or close within the 180-day window. The IRS uses data from Qualified Intermediaries (QIs) to flag non-compliant exchanges.
• Cost Segregation Studies: While cost segregation is a powerful tool for accelerating depreciation, the IRS audits these studies to ensure that property is correctly classified as personal property (5 or 7-year) versus land improvements (15-year) or residential rental property (27.5-year).

The Evolution of IRS Audit Technology: From DIF to Machine Learning

The IRS has come a long way from the manual selection of returns. The Discriminant Information Function (DIF), first introduced in the late 1960s, was a revolutionary step in using statistical models to identify returns with the highest potential for tax change. However, in 2026, the DIF is just one component of a much larger, AI-driven enforcement ecosystem.

The IRS now utilizes Machine Learning (ML) algorithms that can process billions of data points from diverse sources, including social media, property records, and international financial data. These systems are designed to identify "clustering" behaviors—patterns of non-compliance that are common within specific industries or geographic regions. For example, if a high percentage of taxpayers in a particular zip code are claiming unusually high charitable deductions, the AI will flag that entire area for increased scrutiny.

Furthermore, the IRS's Entity Resolution technology allows it to link disparate data points to a single taxpayer. This is particularly effective for identifying taxpayers who use multiple entities or "nominees" to hide income. By creating a comprehensive "taxpayer profile," the IRS can identify inconsistencies that would be invisible to a human auditor or a traditional DIF score.

Client Conversation Script: Explaining Audit Risk

Discussing audit risk with a client requires a balance of professional caution and reassurance. Use the following script to guide the conversation when a client proposes an aggressive tax position.

Advanced Audit Defense Strategies for Practitioners

Beyond basic compliance, senior practitioners should employ advanced strategies to protect clients from unnecessary examinations. This includes the use of Form 8275 (Disclosure Statement) to disclose positions that have a "reasonable basis" but do not meet the "substantial authority" standard. Proper disclosure can often prevent the imposition of accuracy-related penalties under IRC §6662, even if the underlying deduction is eventually disallowed.

Furthermore, practitioners should be familiar with the National Research Program (NRP) audits. Unlike standard audits, NRP audits are random and comprehensive, used by the IRS to update its DIF scoring models. While there is no way to "avoid" an NRP audit, maintaining a "permanent file" for each client with foundational documents (entity formation, operating agreements, basis schedules) ensures that the practitioner is always prepared for a random selection.

Finally, the rise of Artificial Intelligence (AI) in IRS enforcement cannot be ignored. In 2026, the IRS is using machine learning to identify patterns of non-compliance across entire industries. Practitioners should use similar data analytics tools to benchmark their clients' returns against industry averages, identifying potential "outlier" status before the IRS does.

Conclusion: Navigating the New Era of Tax Compliance

The 2026 tax landscape is one of increased transparency and aggressive enforcement. With the funding from the OBBBA and the advancement of AI technology, the IRS has more tools than ever to identify and examine non-compliant returns. However, for the diligent practitioner and the honest taxpayer, this environment also presents an opportunity. By focusing on "bulletproof" documentation, proactive tax planning, and the strategic use of disclosure, practitioners can navigate these audit triggers and provide their clients with the highest level of protection.

The key to success in this new era is not to "hide" from the IRS, but to be so well-prepared that an audit becomes a routine verification rather than a financial catastrophe. As a senior practitioner, your role is to be the "shield" for your clients, using your expertise and the tools provided by Uncle Kam to ensure that every return you file is a model of compliance and strategic planning.