10 things that could trigger an IRS audit

jason harrel
Jason Harrel

Good news. You’re getting a small extension on your federal and state tax deadline this year. Instead of April 15, the due date is Tuesday, April 18. The 15th is a Saturday, and the following Monday is Washington D.C.’s Emancipation Date holiday. I am sure many procrastinators will spend that final weekend wrapping up their returns or completing their extensions.

Heading into tax filing season, there are always concerns as to what triggers an audit. Other than the individuals who came up with the IRS discriminant function, or DIF, system, nobody really knows for sure.

The DIF score is generated by the computer using statistical profiles that compare the tax figures on returns with figures generated from national statistics for taxpayers in similar tax brackets. The higher the DIF score, the more likely an audit. The IRS does not disclose the formula for how this is determined.

Other than the DIF, there are various theories on what triggers audits. From my perspective, a lot of the triggers make sense. Others wouldn’t necessarily trigger an audit, but many taxpayers compute amounts incorrectly and thus make themselves audit targets. Here are some issues that have a higher probability of triggering an audit.


This makes sense. For example, you receive a 1099 for the withdrawal of the money from your 529 plan to pay your kids’ college tuition but fail to report that withdrawal. That will trigger an audit.

Whether the IRS limits your audit to that one issue depends on what else is of interest on your return.

Excessive deductions

Often I meet with a taxpayers undergoing an audit and review their return prior to the start of the audit. They report low amounts of income or even losses on their Schedule C or F, excessive itemized deductions and little to no taxable income.

The question then becomes, how did you afford to live? Most times deductions were overstated or income was omitted. Sometimes, the answer is they borrowed a lot of money or used credit cards, but from a tax administration perspective, such returns often attract scrutiny.

High income

The trend used to be that taxpayers who reported net income of less than $100,000 on Schedule C were a higher target for audit than taxpayers reporting more than that amount. Now, the trend is taxpayers that report more than $200,000 of income are audited more frequently.

The rationale on the lower scale used to be that such individuals likely overstated deductions and/or understated income. Now, the rationale is that high income earners have more opportunities to make errors.

I guess the zone you want to be in now is between $100,000 and $200,000.

Home office

Home office rules are complicated. Make sure you consult a professional regarding them as taxpayers customarily compute the deduction incorrectly.

Real estate losses

Rental real estate losses are per se passive activities such that losses can only be deducted against passive income. Many taxpayers try to claim they are real estate professionals in order to make those losses deductible.

The rules to qualify as a real estate professional are complicated and require a lot of substantiation and documentation. So, before you deduct real estate losses, confer with your tax professional to make sure you are handling the issue correctly.

Excessive deductions, part II

The IRS asks what you do and your occupation code to compare what you report against others in the same industry. For example, if your auto or meals and entertainment are substantially higher than customary for your industry, you will likely be audited.

Additionally, auto and meals and entertainment are customarily not substantiated properly and are an area of frequent adjustment.

Casualty losses

Like the home office, people often report a casualty loss incorrectly and don’t have the proper substantiation.

Before claiming a casualty loss, talk to your tax professional and be prepared to report it correctly and maintain the substantiation.

Gambling losses

People have a misconception about reporting gambling winnings. They often report their losses against the gross winnings and only report the net as the gambling income.

However, all the gambling income is reported on the first page of your Form 1040 and the losses are itemized losses on Schedule A to the extent of your reported winnings.

Where your losses may be limited as a result of limitations on itemized deductions, not only did you lose at the tables, you lose on your tax return.

Unreimbursed employee business expenses

Large amounts of reported unreimbursed employee business expenses are a target because frequently they were reimbursed.

Timely filed or extension?

Answers vary on this question. Some believe you are more likely to be audited by filing on extension, some believe filing timely generates more risk, some think it does not matter.

I am a proponent of filing timely to get the statute of limitations running sooner and expiring sooner. Further, a lot of the audits I handle are for people who filed on extension. Is it because they filed on extension or were just not as careful as they needed to be? Who knows?

When taxpayers are audited, the first thing the IRS typically asks for is all their bank statements and investment account statements. They add up the total deposits and if those deposits do not match the reported gross amounts on the tax return, they are deemed to have unreported income in the amount of the difference.

The burden then is on the taxpayer to prove certain deposits are non-taxable.

So, review your bank statements to make sure you have reported everything deposited to your bank account. This does not mean you do not have to report cash items not deposited, it is just a test to make sure you have not missed something.

Audits are not a fun experience, and for the most part they come down to substantiation. No matter what you report on your return, make sure you have the substantiation for it. If you do not know what you might need, talk to your tax professional.


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