What raises my chance of an IRS audit the most?

Deductions that are large or unusual relative to your reported income are the leading driver, because the IRS scores returns for how far they deviate from statistical norms for similar taxpayers. Other strong signals include claiming 100% business use of a vehicle, reporting business losses year after year, and operating a cash-heavy business where income is easy to underreport.

What is the DIF score?

The Discriminant Function (DIF) score is an IRS scoring system that rates each return for its likelihood of containing errors, based on how its numbers compare to statistical norms for similar returns. A high DIF score doesn't prove anything is wrong — it flags the return for possible human review. Returns with figures far outside the expected range for their income level score higher.

Does claiming a home office trigger an audit?

Not by itself. The home office deduction was once considered a red flag, but it's now common and legitimate for the self-employed. What draws scrutiny is claiming it improperly — deducting space that isn't used regularly and exclusively for business, or claiming amounts that are disproportionate to the business's income. A properly documented home office is not a reason to avoid the deduction.

How many years of losses can a business report before the IRS objects?

There's no hard limit, but the hobby loss rules give the IRS a basis to challenge an activity that consistently loses money. A common guideline treats an activity that turns a profit in at least three of five consecutive years as presumptively a business; falling short doesn't automatically disqualify you, but it shifts the burden to you to show a genuine profit motive.

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IRS Audit Defense

IRS Audit Red Flags: What Actually Raises Your Risk

Most audit fear is misplaced. The real risk drivers are large or unusual deductions relative to income, 100% business-use claims, chronic losses, and cash-heavy operations. Here's what raises the odds — and how to stay clean without playing small.

SMAART Tax Team

March 11, 2026

6 min read