IRS Audits 101: What They Are and Why They Happen

By
Venar Ayar, JD, LLM (Tax)
on
August 19, 2025

Common IRS Audit Red Flags and How to Avoid Them

Nobody wants to receive that dreaded letter from the Internal Revenue Service stating that your tax return has been selected for examination. I’ve seen the panic in my clients’ eyes when they first walk into my office, clutching that IRS notice. An IRS audit can be stressful, time-consuming, and potentially costly if you’re unprepared.

The IRS uses a sophisticated system to identify potential discrepancies and compliance issues, flagging returns that deviate from statistical norms or contain specific triggers.

Knowledge is your best defense against unwanted IRS attention. By understanding common audit red flags, maintaining proper documentation, and adhering to tax laws, you can minimize your chances of facing an audit and position yourself for success if one does occur. At Ayar Law, we’ve helped thousands of clients navigate complex tax situations, and I’m sharing these insights to help you avoid the same pitfalls.

Top Red Flags That Could Trigger an IRS Audit

The IRS uses advanced computer systems and analytical methods to identify tax returns with potential issues. Their automated systems compare your reported income with information provided by employers and financial institutions, looking for discrepancies that might indicate tax compliance problems.

Income Reporting Requirements

Failing to report all taxable income is among the surest ways to trigger IRS attention. The IRS receives information from employers, banks, investment firms, and other financial institutions through forms like W-2s and 1099s, which they match against your tax return.

Discrepancies between reported income and the information the IRS has on file create immediate red flags. This includes:

  • Unreported income from side gigs or freelance work
  • Underreported business income from cash transactions
  • Unreported gambling winnings
  • Unreported rental income
  • Unreported income from digital asset transactions

Even honest mistakes in income reporting can trigger an audit. Always ensure all income sources are accurately reflected on your tax return, regardless of whether you received formal documentation. Your reported income must match what the IRS already knows about your financial activity.

Business Expense Deductions

The IRS closely scrutinizes business expenses, particularly for small business owners and self-employed people. While legitimate business expenses are tax-deductible, the IRS scrutinizes unusually large deductions in relation to business income.

Common business expense audit triggers include:

  • Excessive travel and entertainment deductions
  • Business meals claimed without proper documentation
  • Personal expenses incorrectly classified as business expenses
  • Vehicle expenses without supporting mileage logs
  • Too many deductions compared to your business income

To avoid raising red flags, maintain thorough records that include receipts, invoices, and documentation to establish the business purpose of each expense clearly. Every receipt in your folder can become your strongest ally during an audit. The IRS expects legitimate business expenses to be ordinary and necessary for your industry.

Charitable Contribution Rules

While charitable donations can reduce your taxable income, the IRS pays close attention when contributions appear excessive relative to your adjusted gross income. Documentation requirements increase with donation value:

  • For cash contributions under $250: Bank records or receipts
  • For cash contributions over $250: Written acknowledgment from the charity
  • For non-cash donations over $500: Additional forms and potentially professional appraisals

The IRS examines charitable donations for patterns inconsistent with income level. Claiming $20,000 in charitable contributions on $50,000 of income may raise questions from IRS examiners. Always obtain proper documentation and be prepared to substantiate all charitable deductions.

Foreign Asset Reporting

The IRS has intensified its focus on foreign financial accounts and foreign assets in recent years. Taxpayers must report foreign bank accounts if the aggregate value exceeds $10,000 at any point during the tax year using the Report of Foreign Bank and Financial Accounts (FBAR).

Additionally, certain taxpayers are required to report specified foreign assets on Form 8938 if the value exceeds the threshold amounts. Failing to report foreign assets can result in severe penalties, even if the failure is unintentional.

If you qualify, the foreign earned income exclusion can reduce your tax liability on income earned while living abroad. But proper documentation and meeting specific residency requirements are essential. I’ve seen clients face five-figure penalties for innocent mistakes in this area, so it is crucial that you consult a tax professional if you have foreign assets. 

Digital Asset Transactions and Taxation

Cryptocurrency and other digital asset transactions have become a major IRS enforcement priority. The tax agency now requires explicit reporting of digital asset activity on tax returns.

All digital asset transactions have potential tax implications. The IRS treats digital assets as property, meaning:

  • Capital gains tax applies when selling or exchanging digital assets
  • Mining income is taxable when received
  • Using cryptocurrency to purchase goods or services creates a taxable event

The IRS has increased information gathering from cryptocurrency exchanges and uses sophisticated tracking methods to identify unreported digital asset income. Maintain comprehensive records of all digital asset activities to avoid audit complications and additional taxes.

Cash Transaction Reporting

Cash businesses face higher audit risk because of the ease with which cash income can go unreported. The IRS pays special attention to:

  • Businesses with predominantly cash transactions
  • Reported income inconsistent with lifestyle
  • Cash purchases of high-value assets
  • Suspicious patterns of cash deposits under $10,000

Businesses must report cash transactions exceeding $10,000 using Form 8300. Deliberately structuring transactions to avoid this requirement can lead to serious legal consequences beyond tax issues.

If your business primarily deals in cash, implement thorough record-keeping systems and consider consulting with a tax professional to ensure compliance with all reporting requirements. Your tax software might not alert you to these special reporting requirements.

High-Income Earner Taxation

High-income taxpayers face increased scrutiny from the IRS. The agency focuses on high-income individuals because:

  • Their tax returns are typically more complex.
  • The potential tax recovery is greater.
  • They’re more likely to have foreign assets, complex investments, or business interests.

If your adjusted gross income or modified adjusted gross income places you in higher tax brackets, consider working with an experienced tax attorney who specializes in tax planning and compliance for high-income taxpayers. The right tax professional can help you navigate complex tax laws while minimizing your tax liability.

Small Business and Self-Employment Taxation

Small business owners and self-employed individuals face elevated audit risk compared to W-2 employees. Schedule C (Profit or Loss from Business) filings receive particular scrutiny, especially when:

  • Business losses are claimed for multiple years
  • Business and personal expenses appear commingled
  • The income reported is insufficient to support your lifestyle
  • Home office deductions seem excessive

Self-employment tax compliance is another focus area for IRS examiners. Maintaining clear separation between business and personal finances with dedicated business bank accounts can help demonstrate compliance and reduce audit risk. Your business income must be fully reported to avoid triggering automated matching systems.

Home Office Deduction Rules

The home office deduction allows taxpayers to deduct certain home office expenses when part of their home is used regularly and exclusively for business. However, this deduction is frequently misused, making it an audit trigger when:

  • The deduction seems unusually large compared to business income
  • The space claimed doesn’t align with the business type
  • You’re claiming 100% business use of a space
  • Home office expenses fluctuate dramatically between tax years

To support a legitimate home office deduction, document the square footage used exclusively for business, maintain photographs of your workspace, and keep records of all home office expenses, including utilities, insurance, and maintenance costs. The tax court has consistently upheld the IRS’s strict interpretation of home office rules.

Inconsistent Filing History Consequences

Dramatic changes in your tax situation from year to year can raise red flags. The IRS examines patterns across multiple tax years and notices inconsistencies such as:

  • Significant income fluctuations without a clear explanation
  • Sudden appearance of new deductions or credits
  • Changing filing status frequently
  • Inconsistent reporting of dependents

If legitimate life changes cause significant tax return variations, such as marriage, divorce, business startup, or property sales, include clear documentation with your return to explain these changes and reduce the likelihood of IRS questions. 

Aggressive Tax Scheme Prevention

The IRS actively targets taxpayers participating in “too good to be true” tax strategies. Revenue agents are trained to identify taxpayers using:

  • Abusive tax shelters
  • Schemes promising to eliminate tax liability
  • Frivolous tax arguments challenging the legality of taxes
  • Complex arrangements designed primarily for tax avoidance

Participating in aggressive tax schemes can result not only in an audit but also in substantial penalties and potential criminal prosecution. Consult with a reputable tax attorney before implementing any tax strategy that promises a dramatic tax reduction. The tax court consistently rules against taxpayers who engage in these schemes.

What to Do If You’re Flagged for an Audit

Review the IRS Notice

If you receive an audit notice, carefully review it to understand exactly what the IRS is questioning. Audit notices specify which tax year is under examination and which aspects of your return are being reviewed. Different types of audits require different responses:

  • Correspondence audits can often be handled by mail
  • Office audits require an in-person meeting at an IRS office
  • Field audits involve IRS examiners visiting your home or business

Note all deadlines mentioned in the notice, as missing response timeframes can limit your appeal rights. I know how daunting an audit letter feels when it first arrives, but taking immediate action is crucial.

Gather Documentation

Begin organizing all relevant documentation supporting the items questioned on your tax return. This may include:

  • Income verification (W-2s, 1099s, bank statements)
  • Expense receipts and invoices
  • Investment records and statements
  • Business records, including mileage logs
  • Proof of payment for claimed deductions

The burden of proof generally falls on the taxpayer, so thorough documentation is essential. Organize records by category and tax year to streamline the audit process. Your tax refund may be held until the audit concludes.

Seek Professional Representation

While you can represent yourself in an IRS audit, the complexity of tax laws and the potential consequences make professional representation advisable. A tax attorney can:

  • Communicate with the IRS on your behalf
  • Help prepare and organize documentation
  • Identify potential issues before they become problems
  • Negotiate favorable settlements if additional taxes are owed
  • Protect your rights throughout the audit process

By understanding these common IRS audit red flags and maintaining proper documentation, you can significantly reduce your audit risk while positioning yourself for success if you do face an IRS examination. Remember that tax compliance isn’t about avoiding legitimate deductions. It’s about ensuring you can substantiate all items reported on your tax return with proper documentation and adherence to tax laws.

At Ayar Law, we’ve successfully represented hundreds of clients through IRS audits, often reducing or eliminating proposed tax assessments. Don’t face the IRS alone. Request a free case evaluation today and let our experienced tax attorneys help protect your financial future.

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Venar Ayar Founder and Tax Attorney at Ayar Law

About the Author

Attorney Venar Ayar is an award-winning tax attorney dedicated to helping clients protect themselves from the constant threat of the IRS. Whether you need help with unfiled tax returns, applying for an Installment Agreement, settling for less than you owe through the OIC program, or some other form of IRS debt relief, we’ve got you covered.
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