Construction gets audited more than almost any other kind of self-employed work, because so much of it runs on cash and self-reported numbers. You keep the audit away with two habits: keep your business money separate from your personal money, and keep records at the time, not at tax time. Do both and an audit becomes a non-event, because you can prove every line. Skip them and you are relying on memory against an agency that cross-checks everything.
What to keep, and for how long
The IRS publishes the actual periods rather than one rule of thumb, and two of them run longer than the seven years most people settle on:
| Situation | Keep records for |
|---|---|
| The ordinary case | 3 years |
| You understated income by more than 25% | 6 years |
| You claim a loss from a bad debt or worthless security | 7 years |
| You never filed a return | Indefinitely |
| You filed a fraudulent return | Indefinitely |
| Employment tax records | At least 4 years after the tax is due or paid |
| Anything you own: trucks, plant, tools, the property | Until the limitations period runs out for the year you dispose of it |
That last line is the one that catches contractors, and seven years actively gets it wrong. Expense a truck under Section 179 in 2026 and sell it in 2034 and you need the 2026 purchase invoice and the placed-in-service date in 2034, to work out the recapture. A seven year rule bins it in 2033, the year before you need it. Keep the paperwork for anything you own until three years after you have sold it and filed that year's return, not seven years after you bought it.
Seven years is still a sensible default for everything else:
- Income: every invoice, your contracts, bank statements showing deposits, and any 1099s you received.
- Vehicle: a mileage log kept at the time (date, from, to, purpose, odometer). This is the record contractors most often skip, and it is the first thing challenged.
- Tools and equipment: purchase receipts and the date you put each item into service.
- Subs: the W-9 you collected, the 1099-NECs you filed, and payment records.
- Meals: the receipt plus a note of who you met and what the business was.
- Home office: a sketch or measurement and the utility bills, if you claim it.
What actually gets contractors flagged
The IRS scores every return against similar businesses and cross-matches the forms. These are the ones that light it up:
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Cash income that does not match your deposits. They run a bank-deposit analysis. Unreported cash is the number one construction problem.
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Claiming 100% business use of a vehicle. Almost always challenged. They assume you run it to the store sometimes.
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Treating employees as subs (misclassification). A primary trigger, and its own enforcement priority. The IRS decides it on three questions, not on what the contract says. Behavioral: do you control what the worker does and how he does it? Financial: do you control how he is paid, who supplies the tools, whether costs are reimbursed? Type of relationship: is there a written contract, are there benefits, is the arrangement ongoing, is the work a core part of what you sell? A man who turns up when you say, in your van, with your tools, on your jobs only, is an employee whatever the invoice says.
Two things worth knowing before you assume the worst. You can ask the IRS to decide, on Form SS-8, filed by either side, though it takes at least six months. And if you have treated a category of worker as a sub consistently, filed the 1099s every year, and had a reasonable basis for it, Section 530 relief can excuse the back employment taxes entirely. It is the least known protection in this whole area, and the thing that unlocks it is the paperwork you either filed or did not.
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Your Schedule C not matching the 1099s filed on you. The IRS cross-matches every 1099-NEC.
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Years of losses. Three or more loss years in a row raises the "is this a hobby" question. The test has a name and a number: under the hobby loss rule at section 183(d), an activity that turns a profit in 3 or more of 5 consecutive years is presumed to be a real business, and the IRS has to argue otherwise. Fall outside that and the burden lands on you instead. It is a presumption, not a ban, and a genuine bad run is defensible; it just stops being automatic.
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A huge write-off against low income, like a first-year expensing deduction that wipes out nearly all your profit.
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Big unexplained swings, income jumping or deductions doubling from one year to the next.
The defense is boring and it works
- Separate accounts. A dedicated business checking account and card. Never run business money through your personal account. This one habit does most of the work.
- Records at the time. Log the mile, keep the receipt, note the meal when it happens, not in April from memory.
- Deductions that match the work. If your numbers reflect what you actually did, an audit confirms it and moves on.
Common questions
How likely is a contractor to actually get audited?
Higher than most self-employed people, because construction runs on cash and self-reported numbers, but still low in absolute terms if your records are clean. Bigger Schedule C profits draw more scrutiny than small ones. Solid, contemporaneous records turn an audit into a non-event.
What should I do if I get an IRS audit letter?
Do not ignore it. Most audits are handled entirely by mail, and you respond with the records that back up the lines they ask about. An enrolled agent or CPA can represent you and deal with the IRS for you, usually for less than the amount at stake.
Does claiming the home office deduction trigger an audit?
No, not on its own. It is a normal, legitimate write-off when you use a space regularly and exclusively for business. What draws scrutiny is claiming it when you do not qualify, not claiming it when you do. Skipping a deduction you have earned saves you nothing.
Will filing an extension raise my audit odds?
No. An extension gives you more time to file and does not increase audit risk. It does not extend the time to pay, though, so pay what you can by the April deadline to keep penalties and interest down while you finish the return.
Is it a red flag if I pay my subs in cash?
Not the cash itself, but failing to document it is. Paying subs in cash is legal, but you still need a W-9, a record of the payment, and a 1099-NEC where required, or both your deduction and the sub's income look off. Keep the paper trail.
The honest bit
- These rules and lookback windows are federal and current for 2026. Check specifics at irs.gov.
- If a notice does land, do not ignore it. Most audits are handled by mail, and an enrolled agent or CPA can represent you, usually for less than the exposure.
- This is general guidance, not tax advice for your situation.
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Keep reading
Templates you might need
Sources
- IRS - IRS Audits · How returns are selected for examination and the general period of limitations
- IRS - How long should I keep records · The period of limitations table: 3 years in the ordinary case, 6 where income is understated by more than 25%, 7 for a bad debt or worthless security claim, indefinitely where no return or a fraudulent return was filed, at least 4 years for employment tax records, and property records until the period expires for the year of disposal. Read 2026-09-02.
- IRS - Independent contractor (self-employed) or employee · The common law rules in three categories, behavioral control, financial control and type of relationship; Form SS-8 for a determination by either party, taking at least six months; and Section 530 relief where the business had a reasonable basis and filed all required information returns consistently. Read 2026-09-02.
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