Tax evasion red flags are the patterns on a return that push the IRS from routine processing into a closer look: income the agency already knows about but you didn’t report, deductions that don’t fit your profile, credit claims that don’t hold up, foreign accounts left off the disclosures, cash that doesn’t match the paper trail, and spending that outruns what you say you earn. The consequences range from a computer-generated notice proposing a small adjustment all the way to a felony conviction carrying up to five years in prison. Knowing what trips the system is the practical way to stay on the safe side of it.
How the IRS Decides Which Returns to Look At
Two systems do most of the work. The first is the Discriminant Information Function, a scoring model that compares your return against statistical norms built from random sampling. A high DIF score means your return looks unusual for your income and profession, and returns with the highest scores get routed to human classifiers who decide whether an actual audit is warranted.1Government Accountability Office. How the Internal Revenue Service Selects and Audits Individual Tax Returns
The second is automated document matching. Employers, banks, brokerages, and payment platforms send the IRS copies of the same forms they send you. Under federal regulations, businesses generally must report payments of $600 or more to any single recipient during the year.2eCFR. 26 CFR 1.6041-1 – Return of Information as to Payments of $600 or More The matching program compares those third-party filings against what you reported, line by line, and it doesn’t need a human to notice a discrepancy.
Every flag below plays into one system or the other: something that makes your return statistically odd, or something that contradicts data the IRS already holds.
Income the IRS Already Knows About
Leaving off income that a third party already reported is the fastest way to hear from the IRS. When the matching system finds a gap, you’ll typically get a CP2000 notice proposing additional tax, interest, and possible penalties.3Internal Revenue Service. Topic No. 652, Notice of Underreported Income – CP2000 A CP2000 isn’t an audit and isn’t a bill. It’s a proposal, and it becomes an assessment if you ignore it.
When the understatement is large enough, an accuracy-related penalty of 20 percent of the underpayment applies to negligence or a substantial understatement. For individuals, an understatement is “substantial” when it exceeds the greater of 10 percent of the tax that should have been shown on the return, or $5,000.4Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments A pattern of missing income across multiple years can move the file from civil examination toward a criminal referral.
Deductions That Don’t Fit the Pattern
The DIF is sensitive to deductions that fall outside the normal range for your income and industry. Report $80,000 of self-employment revenue and $75,000 of expenses, and that near-zero margin doesn’t match what the IRS expects your business to look like. A few specific categories draw more scrutiny than others.
Year-After-Year Losses on a Side Activity
Under the hobby loss rules, you can’t deduct losses from an activity that isn’t genuinely aimed at making money.5Office of the Law Revision Counsel. 26 US Code 183 – Activities Not Engaged In For Profit A horse farm or craft business that has lost money five years running while offsetting a salary from a day job is exactly the profile the IRS looks for. Factors that matter: whether you keep businesslike records, whether you’ve changed methods to try to become profitable, and whether the activity has elements of personal recreation.6Internal Revenue Service. Is Your Hobby a For-Profit Endeavor
Vehicle and Meal Expenses
Vehicle and meal deductions are among the most commonly inflated, and the IRS is calibrated for them. Business mileage requires a contemporaneous log: date, start and end locations, business purpose, and miles for each trip, along with odometer readings at the beginning and end of the year. Vague entries like “client meeting” with no destination won’t survive review. The current standard mileage rate is 70 cents per mile for business use.7Internal Revenue Service. Standard Mileage Rates
Business meals remain 50 percent deductible, but you must document who attended, the business relationship, what was discussed, and the amount.8Office of the Law Revision Counsel. 26 USC 274 – Disallowance of Certain Entertainment Expenses Starting in 2026, employer-provided meals on business premises (breakroom coffee, cafeteria food, pantry snacks) are no longer deductible at all. Claims for them after that cutoff are their own red flag.
Home Office and Charitable Contributions
The home office deduction draws extra attention when the percentage of the home claimed for business seems high for the nature of the work. A freelance writer claiming 40 percent of a 3,000-square-foot house looks different from one claiming a spare bedroom, and the space has to be used regularly and exclusively for business.
Charitable contributions get flagged when they look disproportionate to income. A $15,000 donation on a $50,000 salary isn’t impossible, but it stands out. Non-cash donations over $500 require detailed descriptions, and anything over $5,000 generally needs an independent appraisal. Round-number valuations for donated clothing or household goods without documentation are a familiar trigger.
Refundable Credit Claims
Refundable credits pay cash out of the Treasury rather than merely reducing tax, so the IRS scrutinizes them heavily. Paid preparers must complete Form 8867, a due diligence checklist covering the Earned Income Tax Credit, Child Tax Credit, Credit for Other Dependents, American Opportunity Tax Credit, and head-of-household filing status.9Internal Revenue Service. About Form 8867, Paid Preparers Due Diligence Checklist
Common problems: claiming a qualifying child who doesn’t actually live with you for more than half the year, listing a child already claimed on another return, or reporting self-employment income that lands conveniently at the EITC’s maximum-credit sweet spot. The qualifying child must live with you in the United States for more than half the tax year and meet specific relationship requirements.10Internal Revenue Service. Qualifying Child Rules Fabricating or inflating self-employment income to hit the EITC threshold is a well-known fraud pattern the IRS actively targets.
Foreign Accounts and Digital Assets
Holding money overseas isn’t illegal. Failing to disclose it is one of the most aggressively pursued compliance failures the IRS handles. If your foreign financial accounts had a combined value exceeding $10,000 at any point during the year, you must file an FBAR.11Internal Revenue Service. Report of Foreign Bank and Financial Accounts (FBAR) The penalty for a non-willful FBAR violation is now up to $16,536 per account per year after inflation adjustments, and willful violations carry far steeper civil penalties or criminal prosecution.12eCFR. 31 CFR 1010.821 – Penalty Adjustment and Table
FATCA is a separate obligation. It requires reporting specified foreign financial assets on Form 8938 above thresholds that vary by filing status: single filers report when total foreign assets top $50,000 at year-end or $75,000 at any point during the year; joint filers, $100,000 at year-end or $150,000 at any point.13Internal Revenue Service. Summary of FATCA Reporting for US Taxpayers The FBAR and Form 8938 have different thresholds and different filing destinations. Missing one or both when you clearly owe both is a compounding problem.
Cryptocurrency
Every federal income tax return now includes a yes-or-no question asking whether you received, sold, exchanged, or otherwise disposed of any digital asset during the year.14Internal Revenue Service. Digital Assets Answering “no” when exchanges have already reported your transactions is the crypto version of not reporting a W-2. Cash reporting rules under federal law now explicitly treat digital assets as “cash” for purposes of the $10,000 transaction reporting requirement.15Office of the Law Revision Counsel. 26 US Code 6050I – Returns Relating to Cash Received in Trade or Business
Cash Businesses and Structuring
Cash-intensive businesses (restaurants, car washes, laundromats, convenience stores, beauty shops, construction companies paying subcontractors in cash) start with an elevated level of IRS attention because cash receipts are harder to trace. Examiners use industry-specific techniques to reconstruct income from operating inputs, and the agency maintains audit guides for each industry. A business whose reported income doesn’t align with its known operating costs gets a thorough examination.
Any business that receives more than $10,000 in cash from a single buyer, or in related transactions, must file Form 8300 reporting it to the IRS.15Office of the Law Revision Counsel. 26 US Code 6050I – Returns Relating to Cash Received in Trade or Business Breaking a transaction into smaller amounts to stay under $10,000 is structuring, a federal crime carrying up to five years in prison even when the underlying money is completely legitimate. If the structuring is part of a broader pattern of illegal activity exceeding $100,000 in a year, the maximum doubles to ten years.16Office of the Law Revision Counsel. 31 US Code 5324 – Structuring Transactions to Evade Reporting Requirement Multiple $9,500 deposits made specifically to duck the threshold are the classic fact pattern here.
Spending That Outruns Reported Income
The IRS doesn’t always need a specific missing 1099. Under the expenditure method, investigators work from the outside in: if your spending exceeds your reported income and you can’t explain the source of the extra money, the gap is treated as unreported income.17Internal Revenue Service. IRM 9.5.9 Methods of Proof
Investigators pull public real estate records to see what you own, review loan applications where you may have reported a higher income to qualify for financing, and compare those figures against your returns.18Internal Revenue Service. Internal Revenue Manual 4.10.4 – Examination of Income Reporting $30,000 a year while servicing the mortgage on a million-dollar home is the kind of inconsistency that launches a full financial status audit, and the IRS can see it without ever pulling your bank statements.
Round Numbers and Math That Doesn’t Tie
Real business expenses end in odd cents and uneven dollars. A Schedule C reading $5,000 office supplies, $3,000 travel, $2,000 professional development looks like guesswork because it usually is. One round number won’t trigger anything. A return full of them tells reviewers the underlying records are unreliable, and once trust is gone, every figure becomes suspect.
Plain math errors matter too. Numbers on one schedule that don’t tie to another suggest carelessness or manipulation. The IRS can correct simple arithmetic without an audit, but a pattern of errors across a return can push it into a broader review of your filing history.
How Far Back the IRS Can Reach
The statute of limitations sets the window in which the IRS can assess additional tax. The default is three years from the date you filed.19Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection Three exceptions matter:
- Substantial omission (6 years): leaving out more than 25 percent of the gross income shown on your return extends the window to six years.
- Failure to file (unlimited): if you never file, there is no statute of limitations. The IRS can assess at any time.
- Fraud (unlimited): a false or fraudulent return filed with intent to evade tax never starts the clock.
Practically, keep records at least three years after filing. Keep them seven if you have foreign accounts, self-employment income, or any situation where the six-year rule could apply. If you never filed for a given year, keep the records indefinitely.20Internal Revenue Service. How Long Should I Keep Records
When Red Flags Become a Criminal Case
Most flags produce civil results: additional tax, interest, penalties. Willful attempts to evade taxes are different. Tax evasion is a felony punishable by up to five years in prison and a fine of up to $100,000, or $500,000 for a corporation, on top of the civil tax, interest, and fraud penalties still owed.21Office of the Law Revision Counsel. 26 US Code 7201 – Attempt to Evade or Defeat Tax
“Willful” is the pivot. A mistake on your return isn’t a crime. Deliberately hiding income, inventing deductions, or keeping two sets of books is what moves a case from civil noncompliance into criminal territory.
If You’re Already Exposed
The IRS maintains a Voluntary Disclosure Practice for taxpayers who have willfully failed to comply and want to come forward before they get caught. Done properly, it significantly reduces criminal exposure.22Internal Revenue Service. IRS Criminal Investigation Voluntary Disclosure Practice
Timing controls whether the door is even open. Your disclosure must reach the IRS before a civil examination or criminal investigation has started and before a third party has tipped the agency off. The process runs in two parts: a preclearance request, then a full disclosure within 45 days of approval. You’ll file all missing or amended returns, cooperate fully, and pay the tax, interest, and applicable penalties. It isn’t painless. Waiting is worse on every measure that counts.