IRS red flags are patterns or discrepancies in tax returns that can trigger an audit, primarily involving unreported income, excessive or unusual deductions/credits (like large charitable gifts or home office expenses), significant income/loss swings, issues with business/hobby classifications, or dealing with cryptocurrency/foreign accounts, all of which deviate from expected norms and prompt the IRS to verify accuracy. Mismatched third-party income reports (W-2s, 1099s) are a huge trigger, as are inconsistent records and claiming things like 100% business use of a vehicle.
Not reporting all of your income is an easy-to-avoid red flag that can lead to an audit. Taking excessive business tax deductions and mixing business and personal expenses can lead to an audit. The IRS mostly audits tax returns of those earning more than $200,000 and corporations with more than $10 million in assets.
You know the IRS might be investigating you through official mail (first contact), phone calls (often with automated messages to IRS.gov), or in-person visits, but signs of a criminal probe include contact with IRS Criminal Investigation (CI) agents, subpoenas to you or your bank, questions to your accountant/bank, unusual account activity (freezing/refusing transactions), or agents suddenly going silent after an audit. Key indicators are official IRS letters, contact from CI special agents, third-party inquiries, and formal summonses for records, signaling serious scrutiny beyond a simple audit.
Failing to report all taxable income
IRS computers are pretty good at cross-checking the forms with the income shown on your return. A mismatch sends up a red flag and causes the IRS computers to spit out a bill that the IRS will mail to you (these letters don't count as audits for purposes of the IRS's audit rate).
Who must file. Generally, any person in a trade or business who receives more than $10,000 in cash in a single transaction or in related transactions must file a Form 8300.
How far back can the IRS go to audit my return? Generally, the IRS can include returns filed within the last three years in an audit. If we identify a substantial error, we may add additional years. We usually don't go back more than the last six years.
The government has no legal obligation to notify you that you're under investigation. There is no constitutional right to know that prosecutors are building a case against you.
The IRS may initiate criminal proceedings if they suspect a taxpayer has willfully committed tax fraud or tax evasion. This may involve falsifying information on federal tax returns, hiding income, or claiming false deductions.
HMRC gets a tip-off
The most common reasons are: Unhappy or jealous acquaintances who may suspect dubious activity. The existence of a cash-only policy at your business. Living a lifestyle beyond your apparent means.
The IRS does not check every tax return. It does not check the majority of them, but the IRS implements methods that track certain factors that would result in a further examination or audit by them.
The IRS will never initiate contact demanding immediate payment via gift cards, prepaid debit, or wire transfers; threaten immediate arrest or deportation; or contact you first by email, text, or social media; these tactics, especially involving urgent demands for specific payment types or threats, are key signs of a tax scam, as the IRS always mails a bill first and allows time to appeal.
A much higher proportion of Americans living abroad were audited last year than Americans living in the US – 4.3% of international returns were audited compared to just 0.8% of 'domestic' returns. This illustrates that as an expat the audit risk is significantly higher.
The law requires trades and businesses report cash payments of more than $10,000 to the federal government by filing IRS/FinCEN Form 8300, Report of Cash Payments Over $10,000 Received in a Trade or Business PDF.
The "20k rule" refers to the traditional IRS threshold for reporting income from payment apps and online marketplaces on Form 1099-K: over $20,000 in gross payments AND more than 200 transactions in a calendar year. While a law (the American Rescue Plan) temporarily lowered the threshold to $600, recent legislation, the One Big Beautiful Bill Act (OBBBA) (OBBBA), has reinstated the $20,000/200-transaction rule for tax years starting in 2025, providing relief for casual sellers and gig workers.
At a glance: The gift giver pays any gift tax owed, not the receiver. You don't have to report gifts to the IRS unless the amount exceeds $19,000 in 2025. Any gifts exceeding $19,000 in a year must be reported and contribute to your lifetime exclusion amount.
You (or your tax pro) will meet with the IRS agent at an IRS office. The IRS usually starts these audits within a year after you file the return, and wraps them up within three to six months.
Yes, the IRS generally has a 10-year statute of limitations (Collection Statute Expiration Date or CSED) from the tax assessment date to collect unpaid taxes, meaning the debt usually goes away then; however, this clock can be paused or extended by certain events like filing for bankruptcy, entering installment agreements, or living abroad, and there's no time limit for fraud, says the IRS and tax professionals https://www.irs.gov/newsroom/taxpayer-bill-of-rights-6,.
The IRS 3-year rule generally refers to the statute of limitations for claiming a tax refund, which is typically 3 years from when you filed your original return or 2 years from when you paid the tax, whichever is later, for the IRS to process your claim. For an audit, the IRS generally has 3 years from the date your return was filed or due (whichever is later) to assess additional tax, though this can extend to 6 years if you significantly underreport income or omit foreign income.
The IRS probably already knows about many of your financial accounts, and the IRS can get information on how much is there. But, in reality, the IRS rarely digs deeper into your bank and financial accounts unless you're being audited or the IRS is collecting back taxes from you.
The IRS escalates its collection efforts when the amount owed exceeds $25,000, which can result in severe penalties such as asset seizure, bank levy, wage garnishment, and even passport revocation. If you're unsure how much you owe, you can find more information and guidance here.