Receiving an IRS audit letter is one of the most anxiety-inducing moments in a person's financial life. Most people's first instinct is panic. Their second instinct is to call a tax attorney.
In most cases, neither reaction is necessary. The majority of IRS audits are routine correspondence audits that are resolved by mail, often in a matter of weeks, by simply providing the documentation the IRS is asking for.
Understanding what type of audit you're facing — and how to respond correctly — is all you need in most situations.
The Three Types of IRS Audits
1. Correspondence Audit (Most Common)
A correspondence audit is conducted entirely by mail. The IRS sends a letter — typically a CP2000, CP2501, or a letter in the 5XX series — requesting documentation to support a specific item on your return.
Common triggers for correspondence audits:
- A 1099 or W-2 that wasn't reported on your return (income mismatch)
- Charitable deductions above statistical norms for your income level
- Business expenses that seem high relative to your income
- Education credits or earned income credit claims that need verification
What to do: Read the letter carefully. The IRS will identify exactly what they're questioning and what documentation they want. Gather that documentation — bank statements, receipts, employer letters — and respond by the deadline (usually 30–60 days).
2. Office Audit
An office audit requires you to come to an IRS office and meet with an examiner in person (or bring your documents to them). These are more involved than correspondence audits and typically cover multiple items on your return.
You'll receive a letter explaining the date, time, location, and a list of documents to bring. You can (and for office audits, usually should) bring a tax professional to represent you.
What to do: Don't go alone if the dollar amounts at issue are significant. An enrolled agent, CPA, or tax attorney can respond to questions strategically and knows which documents to provide — and which to leave home.
3. Field Audit
A field audit is the most serious type. An IRS revenue agent comes to your home, business, or your representative's office to review your records. Field audits are typically reserved for:
- Business owners with complex returns
- High-income taxpayers
- Situations where the IRS suspects significant unreported income or fraud
If you receive a field audit notice, you should work with a tax professional. The revenue agent has significant authority and a field audit can expand in scope once it begins.
What Triggers an IRS Audit
The IRS uses automated algorithms to flag returns that deviate significantly from statistical norms. Common audit triggers include:
- Income inconsistencies: Reported income significantly lower than third-party forms (W-2s, 1099s) show
- High deduction-to-income ratios: Unusually large charitable, business, or home office deductions relative to your income
- Claiming 100% business use of a vehicle: Almost always flagged
- Self-employment losses every year: Especially if combined with W-2 income suggesting the activity isn't a real business
- Cash-intensive businesses: Restaurants, salons, contractors — industries with high potential for unreported cash income
- Foreign bank accounts: FBAR filing requirements and foreign income are heavily scrutinized
- Math errors: Sometimes a simple miscalculation leads to correspondence
Note: Most audits are random or driven by data matching — getting audited doesn't mean the IRS suspects you of fraud.
How to Respond to a Correspondence Audit
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Read the entire letter before doing anything. Identify: what tax year, what line items, what documentation is requested, and the response deadline.
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Gather your documentation: Bank statements, credit card statements, receipts, employer letters, canceled checks. Organize them to match the items the IRS is questioning.
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Write a cover letter: Don't just mail a stack of documents. Write a short letter that identifies the notice number, explains what you're enclosing, and clearly addresses each item the IRS questioned. Example: "Regarding the charitable deduction on Line 40 of your Notice: enclosed are receipts and bank statements documenting donations totaling $X to Y organizations."
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Send by certified mail with return receipt: This creates a timestamp and proof of delivery.
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Keep a copy of everything you send.
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Respond by the deadline: If you need more time, call the number on the notice and request an extension — they usually grant 30 additional days easily.
What to Never Do When Audited
- Don't ignore it: Ignoring an audit notice results in the IRS assessing additional tax based on their figures, which are often worse than what you actually owe. You then have limited ability to dispute.
- Don't send original documents: Always send copies. The IRS loses documents.
- Don't volunteer information beyond what's asked: Answer the specific question. Don't include documentation for items the IRS isn't questioning — you may inadvertently invite scrutiny of those items.
- Don't lie or fabricate documents: Intentional falsification during an audit is a federal crime.
- Don't assume the IRS is right: If they propose changes you disagree with, you have the right to appeal. The IRS examiner's initial proposal is not the final word.
The Statute of Limitations on Audits
The IRS generally has three years from the date you filed your return to audit it. Key exceptions:
- Six years: If you omitted more than 25% of your gross income
- No limit: If you filed a fraudulent return or didn't file at all
- Three years from amended return: If you file an amended return that increases your liability
This means old returns eventually become safe. If you're audited for a year from seven years ago, you can raise the statute of limitations as a defense (unless one of the exceptions applies).
After the Audit: Your Options
If the IRS proposes additional tax and you disagree:
- Provide additional documentation: If you missed something, you can supplement your response
- Request a conference with the examiner's supervisor: For correspondence audits, you can escalate within the IRS
- Appeal to the IRS Independent Office of Appeals: A separate IRS division that objectively reviews disputes — many cases settle favorably here
- Petition Tax Court: If you receive a Statutory Notice of Deficiency, you can challenge the IRS in Tax Court without paying the disputed tax first
- Pay and file a refund claim: Pay the tax, then sue for a refund in U.S. District Court or the Court of Federal Claims
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