The honest answer is that you avoid red flags by reporting accurate numbers. The IRS uses algorithms to compare your return against others in your industry and income bracket. When your numbers look unusual relative to what’s expected, that’s what triggers a closer look. So the goal isn’t to game the system. It’s to make sure your return reflects reality and that you have the documentation to prove it.

That said, there are specific things that trades and service businesses do (often without realizing it) that draw attention.

Reporting round numbers is a classic one. If every line on your return ends in zero, it looks like you’re guessing instead of working from actual records. Real expenses don’t land on $5,000 or $10,000. They land on $4,837 or $11,243. Precise numbers signal that you’re working from books, not estimates.

Vehicle deductions without a mileage log are a big trigger. The IRS knows contractors drive a lot for work. They also know most people claiming 100% business use on a truck are stretching the truth. Keep a mileage log, even a simple app that runs in the background. If you’re audited, “I use it for work all the time” isn’t documentation.

Large subcontractor payments without corresponding 1099 filings will cause problems. If you paid someone $20,000 for sub work and didn’t file a 1099-NEC, the IRS sees a mismatch. Either you’re deducting payments you can’t verify, or you’re contributing to unreported income. Both draw scrutiny. File your 1099s for every sub you pay $600 or more during the year.

Consistently showing losses on Schedule C while maintaining your lifestyle is another flag. If your business lost $15,000 three years in a row but you’re making mortgage payments and buying equipment, the IRS questions whether those losses are real or whether income is going unreported. For cash-heavy trades businesses, this is an area they look at closely.

Deductions that are disproportionate to your income stand out. If you report $80,000 in revenue and $25,000 in meals and travel, that ratio doesn’t pass the smell test for a local plumbing or landscaping business. Your deductions should make sense for the type and size of work you do.

Mixing personal and business expenses creates problems you might not see until an audit. That family dinner on the business card, the Home Depot run that was half personal and half job materials. When personal spending gets categorized as business deductions, your numbers skew in ways that algorithms can detect. Separate your accounts and only deduct what’s actually for the business.

The common thread in all of this is that bookkeeping for trades businesses done properly throughout the year eliminates most red flags naturally. When every transaction is recorded, categorized correctly, and tied to documentation, your return reflects what actually happened. There’s nothing unusual to flag because the numbers are real.

If you’ve been filing returns based on bank statements and best guesses, or if your books are months behind when tax season arrives, that’s where mistakes creep in. Rushed business tax returns built on incomplete records lead to round numbers, missed 1099 filings, and deductions you can’t support. The fix isn’t a last-minute review of your return. It’s keeping your books clean all year so the return practically writes itself.