Most people will never be audited. The overall audit rate for individual tax returns is 0.44% [1]. That's fewer than 1 in 200 returns. If you file a straightforward W-2 return with a standard deduction, the odds of the IRS selecting you for examination are vanishingly small.
But "audit" is one of those words that carries more weight than the numbers justify. It's the financial equivalent of "the principal's office." The fear is outsized. This guide is designed to shrink it back to the right proportions by explaining exactly what triggers an audit, what happens during one, and how to get through it without losing sleep or money you don't owe.
30-Second Summary: The IRS audits fewer than 0.5% of individual returns. Most audits are by mail, not in person. High income, large deductions relative to income, unreported 1099 income, and cash-heavy businesses are the main triggers. You have the right to representation and appeal. For simple correspondence audits, you can usually handle it yourself.
What Actually Triggers an Audit
The IRS doesn't pick returns at random (well, almost never). Selection is driven by a combination of computer scoring, document matching, and related investigations.
The DIF Score
Every return gets run through the Discriminant Information Function (DIF), an algorithm that compares your return against statistical norms for similar taxpayers [2]. If your deductions, income patterns, or credits look significantly different from returns in your income bracket, your DIF score goes up. A high score means your return gets flagged for human review.
The IRS doesn't publish the DIF formula. But the patterns that raise it are well-understood:
Common Triggers
| Trigger | Why It Flags |
|---|
| Income over $200,000 | Higher audit rates at every bracket above $200k [1] |
| Income over $10 million | Audit rate jumps to 8.7% [1] |
| Unreported income (1099 mismatch) | IRS computers match every 1099 filed against your return |
| Large Schedule C losses | Cash businesses with consistent losses look like hobby deductions |
| Unusually high deductions vs. income | Charitable donations of 40% of income, for example |
| EITC claims | 0.9% to 1.27% audit rate, higher than average for that income level [3] |
| Round numbers everywhere | $5,000, $10,000, $15,000 on every line suggests estimation, not record-keeping |
| Home office deduction | Not inherently risky, but historically over-claimed |
| Related returns | Your business partner gets audited; you might too |
The biggest single trigger is unreported income. When a client files a 1099-NEC saying they paid you $4,000, and your tax return doesn't include that $4,000, the IRS computer sends an automated notice before a human ever looks at your file.
That automated notice (a CP2000) is technically not a formal audit. It's an "underreporter inquiry" [4]. But it feels like one, and the resolution process is similar.
The Three Types of Audits
Not all audits are created equal. The IRS conducts three types, and they differ enormously in scope and intensity.
Correspondence Audit (Mail)
The most common type, representing 77.3% of all individual audits in FY 2023 [1]. The IRS sends you a letter asking for documentation on one or two specific items. Maybe they want proof of a charitable donation. Maybe they need a receipt for a business expense.
You respond by mail (or sometimes online) with the requested documents. If the IRS agrees, the audit closes. If they disagree, they propose changes and you can accept or appeal.
This is the audit equivalent of a parking ticket. Annoying, but manageable.
Office Audit
The IRS asks you to come to a local IRS office with your records. These cover broader issues than correspondence audits, often involving multiple deductions or a range of income sources.
You can bring a tax professional (CPA, Enrolled Agent, or tax attorney) to represent you. In fact, you can authorize a representative to go instead of you entirely.
Field Audit
An IRS revenue agent comes to your home or business. This is the full-scope examination. They review books, records, and sometimes interview you. Field audits are rare for individual taxpayers and more common for businesses or high-net-worth individuals.
If you get one of these, hire a professional. That's not a suggestion.
What Happens During a Correspondence Audit
Since most readers will only ever encounter this type, let's walk through it.
Step 1: You receive a letter (not an email, not a phone call) from the IRS. The IRS will never initiate contact via email or text. If you get an "audit notice" by email, it's a scam. The letter identifies the tax year, the specific items under review, and what documentation they need.
Step 2: Gather your records. Receipts, bank statements, 1099s, canceled checks, mileage logs. The letter tells you exactly what they want.
Step 3: Send copies (never originals) to the address on the letter by the deadline listed (usually 30 days, sometimes 60).
Step 4: The IRS reviews your response. Three outcomes:
- They agree with your documents. Audit closed. No change.
- They partially agree. They propose an adjustment. You can accept or dispute.
- They disagree entirely. They issue a proposed change. You can appeal.
If you agree with the proposed change, you sign the agreement and pay any additional tax owed (plus interest). If you disagree, you have 30 days to request an appeals conference with the IRS Office of Appeals [5].
Worked Example: The Missing 1099
Aisha, a freelance graphic designer, receives a CP2000 notice in September 2025 for her 2023 tax return. The IRS says she failed to report $4,000 from a client who filed a 1099-NEC.
Aisha actually did receive the $4,000. She just forgot to include it on her return.
| Item | Amount |
|---|
| Unreported income | $4,000 |
| Federal income tax (22% bracket) | $880 |
| Self-employment tax (15.3%) | $612 |
| Total additional tax | $1,492 |
| Failure-to-pay penalty (0.5%/mo × 12 months) | $89.52 |
| Interest (7% annual, ~12 months) | ~$110 |
| Total bill | ~$1,692 |
A four-thousand-dollar oversight became a $1,692 bill. Aisha responds to the CP2000, agrees with the adjustment, and pays through IRS Direct Pay. Audit closed.
Had she ignored the letter, the IRS would have assessed the tax automatically, added higher penalties, and eventually started collection activity.
Your Rights During an Audit
The Taxpayer Bill of Rights guarantees several protections [5]:
- The right to be informed. The IRS must explain what they're examining and why.
- The right to professional representation. You can have a CPA, Enrolled Agent, or attorney represent you at any point. They can speak to the IRS on your behalf.
- The right to appeal. If you disagree with the IRS's findings, you can request an independent review by the Office of Appeals before any court proceedings.
- The right to a fair and just tax system. Penalties can be abated if you had reasonable cause for an error.
If you receive an audit notice, do not ignore it. Silence is the worst strategy. The IRS will proceed without your input and assess taxes based on their own calculations, which are almost always less favorable to you.
How Far Back Can the IRS Go?
The general statute of limitations for audits is three years from the date you filed [6]. File your 2024 return on April 15, 2025? The IRS generally has until April 15, 2028 to examine it.
Exceptions:
- Substantial understatement (you understated income by more than 25%): 6 years
- Fraud or failure to file: No time limit. Ever.
This is why filing a return is always better than not filing one. A filed return starts the clock. No return means the IRS can come back at any time.
When to Handle It Yourself vs. Hire a Pro
| Situation | Do It Yourself? | Hire a Pro? |
|---|
| Simple correspondence audit (missing receipt) | Yes | Optional |
| CP2000 for a clearly valid 1099 | Yes | Optional |
| Office audit covering multiple deductions | Maybe | Recommended |
| Field audit at your home or business | No | Essential |
| Any dispute involving potential fraud | Absolutely not | Essential (tax attorney) |
For choosing a professional: an Enrolled Agent (EA) specializes in tax representation and is often the most cost-effective choice for audits. A CPA brings broader financial expertise. A tax attorney is necessary when fraud or criminal liability is in question.
Reducing Your Audit Risk
You can't eliminate audit risk entirely, but you can keep it low:
Report all income. The IRS receives copies of every W-2, 1099, and K-1 filed. If they have it, you need to report it.
Keep receipts. Digital photos of paper receipts work fine. Apps like Dext or even a dedicated Google Drive folder save headaches years later.
Avoid round numbers. "$4,832 in charitable donations" is more credible than "$5,000." Odd specificity signals real record-keeping.
Be honest about deductions. Claiming a home office that's also your kids' playroom invites scrutiny. Claiming business meals at 100% when the deduction is 50% invites correction.
Don't skip filing. The IRS can file a return on your behalf (called a Substitute for Return), and it won't include any deductions or credits you're entitled to. It's always the worst-case calculation.
Your Next Move
- If you received an audit letter, read it carefully and note the response deadline. Don't panic. Most audits are correspondence-only.
- Gather the specific documents requested. Send copies, not originals.
- If you agree with the IRS's proposed changes, sign the agreement and pay. Use IRS payment options if you can't pay in full.
- If you disagree, write a clear response with supporting documentation. You have the right to appeal.
- For office or field audits, hire an Enrolled Agent or CPA before your appointment.
- Going forward, keep organized records and report every dollar of income. The best audit defense is a boring, accurate return.
If an audit uncovers a mistake you made, you might need to understand the amended return process. And to ensure your withholding is correct going forward (so you don't owe a large balance that attracts attention), review our guide to filling out your W-4.
For a broader understanding of how the IRS calculates what you owe, use our tax bracket calculator or explore how marginal tax rates work.
The IRS recommended $31.9 billion in additional tax through examinations in FY 2023 [1]. That's a big number. But spread across 266 million processed returns, your individual odds of being part of it are slim. File honestly, keep records, respond to any letters, and you'll be fine.
References
- Internal Revenue Service. (2024). IRS Data Book, 2023. IRS.gov. https://www.irs.gov/pub/irs-pdf/p55b.pdf
- Internal Revenue Service. (2024). IRS Audits. IRS.gov. https://www.irs.gov/businesses/small-businesses-self-employed/irs-audits
- Tax Policy Center. (2024). EITC Audit Rates. TaxPolicyCenter.org.
- Internal Revenue Service. (2024). Understanding Your CP2000 Notice. IRS.gov. https://www.irs.gov/individuals/understanding-your-cp2000-notice
- Internal Revenue Service. (2024). Publication 1: Your Rights as a Taxpayer. IRS.gov. https://www.irs.gov/pub/irs-pdf/p1.pdf
- Legal Information Institute. (Current). 26 U.S. Code § 6501 - Limitations on Assessment and Collection. Cornell Law School. https://www.law.cornell.edu/uscode/text/26/6501
