The IRS notifies you of an audit only by mail, never by phone or email, sending a letter detailing the tax year, reason for examination, required documents, and instructions for mail or in-person review (office or field audit). This official letter will come via U.S. Postal Service, often requiring a signature, and provides contact info for the assigned agent. Always check that the notice includes an agent's name, phone number, and IRS ID, and be wary of scams demanding immediate payment, as the IRS won't threaten arrest or demand gift cards.
The IRS performs audits by mail or in person. The notice you receive will have specific information about why your return is being examined, what documents if any they need from you, and how you should proceed. Once the IRS completes the examination, it may accept your return as filed or propose changes.
An IRS audit letter typically contains the taxpayer's name, tax ID number, contact information, and a request for additional documentation to support claims on the tax return. It may also include the name of the IRS officer handling the case and invite the taxpayer to a meeting.
Filers most commonly receive letters from the IRS notifying them of the examination in the fall or winter months of the previous tax filing year. Yet, the auditors can mail the notifications throughout the year.
Unreported income
The IRS receives copies of your W-2s and 1099s, and their systems automatically compare this data to the amounts you report on your tax return. A discrepancy, such as a 1099 that isn't reported on your return, could trigger further review.
The IRS uses a combination of automated and human processes to select which tax returns to audit. Not reporting all of your income is an easy-to-avoid red flag that can lead to an audit. Taking excessive business tax deductions and mixing business and personal expenses can lead to an audit.
What happens during an audit? Internal audit conducts assurance audits through a five-phase process which includes selection, planning, conducting fieldwork, reporting results, and following up on corrective action plans.
The overall odds of an IRS audit are low, about 4 out of every 1,000 returns. However, high-net-worth individuals are more likely to be targeted due to complex income sources, large deductions, and sophisticated financial structures.
The IRS $600 rule refers to a change in reporting requirements for third-party payment apps (like Venmo, PayPal) for taxable income from goods and services, where platforms must send a Form 1099-K if you receive over $600 in a year, intended to capture gig economy/side hustle income, though delays and phased implementation have adjusted the timeline, with current rules for 2024 using a higher threshold ($5,000) before fully phasing to $600 for future years, but remember all taxable income, regardless of form, must always be reported.
The 5 Cs of audit (Criteria, Condition, Cause, Consequence, Corrective Action) are a framework for structuring clear, actionable audit findings, explaining what should be (Criteria), what is found (Condition), why it happened (Cause), what the impact is (Consequence/Effect), and how to fix it (Corrective Action/Recommendation) to drive organizational improvement and compliance.
What Not to Say During an Audit?
If the IRS proves willful misconduct, you may face criminal charges, fines, and— in severe cases—prison. Most taxpayers, however, receive civil penalties only. Refunds are paused until the audit finishes.
Revenue agents – examinations (audits)
They may meet you at an IRS office or visit your home, business or accountant's office. A visit may require a tour of your business or your authorized power of attorney. Before a visit: The agent contacts you by mail. After, they may call to discuss your audit.
You (or your tax pro) will meet with the IRS agent at an IRS office. The IRS usually starts these audits within a year after you file the return, and wraps them up within three to six months.
If the IRS decides that your return merits a second glance, you'll be issued a CP05 Notice 1 . This notice lets you know that your return is being reviewed to verify any or all of the following: Your income. Your tax withholding.
The IRS "10k rule" primarily refers to the requirement for businesses and financial institutions to report cash transactions over $10,000 by filing Form 8300 (for businesses) or a Currency Transaction Report (CTR) (for banks), under the Bank Secrecy Act. This rule helps combat money laundering, tax evasion, and terrorist financing, requiring reporting for single transactions or related transactions totaling over $10,000 in cash within a year, with penalties for non-compliance.
The "20k rule" refers to the traditional IRS threshold for reporting income from payment apps and online marketplaces on Form 1099-K: over $20,000 in gross payments AND more than 200 transactions in a calendar year. While a law (the American Rescue Plan) temporarily lowered the threshold to $600, recent legislation, the One Big Beautiful Bill Act (OBBBA) (OBBBA), has reinstated the $20,000/200-transaction rule for tax years starting in 2025, providing relief for casual sellers and gig workers.
The IRS generally audits a larger share of high-income taxpayers than those with lower incomes, as illustrated in Figure 1. However, those who claim the Earned Income Tax Credit (EITC)—who typically have low incomes—are much more likely to face an audit than all but the highest-income taxpayers.
You know the IRS might be investigating you through official mail (first contact), phone calls (often with automated messages to IRS.gov), or in-person visits, but signs of a criminal probe include contact with IRS Criminal Investigation (CI) agents, subpoenas to you or your bank, questions to your accountant/bank, unusual account activity (freezing/refusing transactions), or agents suddenly going silent after an audit. Key indicators are official IRS letters, contact from CI special agents, third-party inquiries, and formal summonses for records, signaling serious scrutiny beyond a simple audit.
Audit tips and tricks key takeaways:
Five Common Audit Findings and How to Address Them: Insights from Page Kirk
The Final Phase: Audit Reporting
The last phase of the audit process involves finalizing the audit report and communicating the findings to the organization's management and stakeholders.