What Is an IRS Audit? Types, Triggers, and Timeframes

An IRS audit is a review of your federal tax return in which the agency verifies that the income, deductions, and credits you reported are accurate and properly documented. Fewer than 1% of individual returns are audited in a typical year, though that rate climbs sharply with income, reaching 11% for taxpayers reporting more than $10 million in total positive income in the most recent year with complete data.¹ An audit can end with no change to your return, additional tax with penalties and interest, or occasionally a refund if you overpaid.

How the IRS Picks Returns to Audit

Federal law gives the IRS broad authority to examine anyone who may owe tax, including the power to review books and records and summon witnesses.²³ In practice, most audits start with a computer. The Discriminant Function System scores every return on the likelihood that an examination would produce a change in tax; high-scoring returns go to a human classifier who decides whether to pursue an audit.⁴ A separate formula flags returns that appear to have unreported income based on patterns like negative cash flow or mismatches with third-party data.⁵

You can also get pulled in because someone connected to you is already under exam. A business partner, investor, or related entity being audited can bring your return into the spotlight if the IRS sees links worth checking.

What Tends to Trigger a Closer Look

High income is the most reliable predictor. Taxpayers earning over $1 million face audit rates two to twenty times higher than those earning under $200,000.¹ Beyond that, the IRS pays attention to deductions that look out of scale with reported income. Claiming $50,000 in charitable contributions on $100,000 of income will almost certainly earn a second look.

Schedule C filers face elevated risk because they report their own income and claim their own expenses. Reporting business losses year after year can invite scrutiny under the hobby-loss rules. Cash-heavy operations draw attention because the IRS uses bank deposit analysis and industry benchmarks to test reported revenue. Claiming 100% business use of a personal vehicle is another common red flag.

Earned Income Tax Credit claims have some of the highest error rates on individual returns, so they get disproportionate audit attention. Amended returns claiming large refunds, unreported foreign accounts aggregating over $10,000 at any point in the year, and large rental property losses can all raise your odds.

The Three Types of Audits

Which type of audit you face depends on how complex the issues are.⁶

Correspondence audits happen by mail. The IRS asks for documentation on specific items, you send it in, and the examiner never meets you. These are the most common type, making up roughly 85% of individual audits.
Office audits require you to visit a local IRS office. The scope is still narrow, but the issues are usually more involved than a mail review can settle.
Field audits bring a revenue agent to your home, business, or accountant’s office for a thorough review of records and sometimes physical assets. These are reserved for the most complex returns and are generally scheduled where the books are kept.⁷

If a field audit would disrupt your business, you can ask in writing for the IRS to move it to a Service office. Exams must be scheduled during normal business hours, and if a location poses a safety concern, the agent can relocate the examination without a request from you.⁷ Every audit begins with a letter. The IRS does not open audits by phone or email.⁶

What You’ll Need to Produce

When the exam opens, the IRS sends Form 4564, the Information Document Request, listing the specific records it wants.⁸ The request targets whatever line items are under review: receipts, canceled checks, bank statements, deeds, loan agreements, mortgage records. Organize what you send chronologically by tax year and tie each document to the specific return line it supports. A summary sheet explaining what each document proves reduces follow-up requests.

If a receipt is missing, the IRS may accept bank statements, credit card records, or a contemporaneous diary log as secondary evidence. “May accept” carries the weight in that sentence: the weaker your documentation, the easier it is for the examiner to disallow the deduction. Keep copies of everything you hand over.

The baseline record-retention rule is three years from the date you filed. That window stretches in specific situations:⁹

Six years if you omitted income exceeding 25% of the gross income shown on the return.
Seven years if you claimed a deduction for worthless securities or bad debt.
Four years for employment tax records, measured from the date the tax was due or paid, whichever is later.
Indefinitely if you filed a fraudulent return or never filed at all.

Your Rights During the Audit

The Taxpayer Bill of Rights sets out ten protections that apply throughout every audit. Among the most important: the right to be informed of IRS decisions in clear language, the right to pay no more than the correct amount of tax (including penalties and interest), the right to challenge the IRS’s position and be heard, and the right to appeal in an independent forum.¹⁰

You have the right to representation at any point. If you tell the examiner during an interview that you want to consult an attorney, CPA, or enrolled agent, the examiner must stop the interview immediately, even if you’ve already answered questions.¹¹ Your representative can attend interviews in your place with a signed Form 2848 power of attorney, and the IRS generally cannot force you to appear personally unless it issues a formal summons.¹² Eligible representatives include attorneys, CPAs, enrolled agents, enrolled actuaries, and in limited circumstances the tax preparer who signed the return.

You can audio-record any in-person interview using your own equipment as long as you notify the IRS in advance. The IRS can also record, but must tell you first.¹¹ If the process is causing financial hardship or your case isn’t being resolved, you can request help from the Taxpayer Advocate Service by filing Form 911.¹⁰

How Long the IRS Has to Audit

The IRS generally has three years from the date you filed your return to assess additional tax.¹³ The window extends to six years if you omitted more than 25% of your gross income.⁹ There is no time limit at all in three situations: a fraudulent return, deliberate tax evasion, or a return you never filed.

Before the statute expires, the IRS may ask you to sign a consent extending it. You have the right to refuse or to limit the extension to specific issues or a specific period. Refusing is not without cost: the IRS may respond by issuing a quick assessment on incomplete information rather than take more time to work through your case.

How the Audit Ends

When the examination wraps up, the IRS issues an Examination Report with one of three results:⁶

No change. You substantiated everything the IRS questioned, and the case closes without adjustment.
Agreed. You accept the proposed changes, sign the report, and pay any additional tax, penalties, and interest.
Disagreed. You can request a conference with the examiner’s manager, pursue mediation, or move into the formal appeals process.

Audits can occasionally reveal that you overpaid, in which case you receive a refund. That’s the exception. Audits selected because of high DIF scores overwhelmingly result in additional tax owed.

Penalties and Interest if You Owe

An audit adjustment isn’t just the additional tax. Penalties and interest stack on top and can significantly enlarge the final bill.

The accuracy-related penalty adds 20% of the underpayment when the IRS finds negligence, disregard of tax rules, or a substantial understatement of income.¹⁴ Negligence here means failing to make a reasonable effort to comply with the tax code, and this is the penalty most audited taxpayers see.

The civil fraud penalty is far heavier: 75% of the portion of the underpayment attributable to fraud.¹⁵ Once the IRS establishes that any part of the underpayment was fraudulent, it treats the entire underpayment as fraud unless you prove otherwise. On a joint return, only the spouse responsible for the fraud is liable for the penalty.

If the audit reveals you should have filed a return but didn’t, the failure-to-file penalty is 5% of the unpaid tax for each month the return is late, capped at 25%.¹⁶

Interest runs from the original due date of the return, not from the date the audit closes. The IRS sets the rate quarterly at the federal short-term rate plus three percentage points and compounds it daily. The underpayment rate for individuals is 7% for the first quarter of 2026.¹⁷ An audit that takes two years to conclude generates real interest even on a modest underpayment.

Disagreeing With the Result

If you dispute the audit findings, there is a structured path to challenge them before litigation.

After the exam closes, the IRS sends a “30-day letter” explaining the proposed changes and your right to appeal. You generally have 30 days from the letter’s date to file a written protest requesting a conference with the IRS Independent Office of Appeals.¹⁸

If You Can’t Pay the Balance

An audit balance doesn’t have to be paid in a single check. Individuals who owe $50,000 or less in combined tax, penalties, and interest, and who have filed all required returns, can apply online for a long-term installment agreement.²⁰ Setup fees are lower for direct debit and for online applications, and they’re waived entirely for low-income taxpayers (adjusted gross income at or below 250% of the federal poverty level) who choose direct debit. Penalties and interest keep accruing on the unpaid balance, so stretching payments has a real cost.

If you genuinely cannot pay the full amount, you can propose an offer in compromise to settle for less than owed. The IRS evaluates your income, expenses, asset equity, and ability to pay to decide whether the offer represents the most it can realistically collect.²¹ You must have filed all required returns, made all required estimated payments, and not be in an open bankruptcy. Most offers are rejected, so this is a last resort rather than a routine negotiating tool.

Once tax is formally assessed, the IRS has 10 years to collect through levies or court proceedings, after which the debt expires.²² Entering an installment agreement can extend that clock, which matters if you’re negotiating terms on an older balance.

1
Internal Revenue Service. Compliance Presence
2
Office of the Law Revision Counsel. 26 USC 7601 – Canvass of Districts for Taxable Persons and Objects
3
Office of the Law Revision Counsel. 26 USC 7602 – Examination of Books and Witnesses
4
U.S. Government Accountability Office. How the Internal Revenue Service Selects and Audits Individual Income Tax Returns
5
Internal Revenue Service. Test of Unreported Income (UI) DIF Scores
6
Internal Revenue Service. IRS Audits
7
Internal Revenue Service, Treasury. 26 CFR 301.7605-1 – Time and Place of Examination
8
Internal Revenue Service. Form 4564 – Information Document Request
9
Internal Revenue Service. How Long Should I Keep Records
10
Internal Revenue Service. Taxpayer Bill of Rights
11
Office of the Law Revision Counsel. 26 USC 7521 – Procedures Involving Taxpayer Interviews
12
Internal Revenue Service. Instructions for Form 2848
13
Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection
14
Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments
15
Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty
16
Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
17
Internal Revenue Service. Quarterly Interest Rates
18
Internal Revenue Service. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court
20
Internal Revenue Service. Payment Plans; Installment Agreements
21
Internal Revenue Service. Offer in Compromise
22
Office of the Law Revision Counsel. 26 USC 6502 – Collection After Assessment