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IRS audit triggers: the patterns that select small practices

Summary

What draws IRS attention to a small practice is rarely bad luck; it is pattern. Most returns are scored and matched automatically, so the flags are deductions that look outsized against income, a home-office or vehicle claim that fails the rules, a worker treated as a 1099 who looks like an employee, late payroll deposits, and income that does not match the 1099s and card-settlement forms the agency already holds. Clean, substantiated books turn nearly all of it into a letter you can answer in an afternoon.

By Gale Editorial · Updated 2026-07-27. Every figure cited to a dated source. How we write.

How the IRS actually selects a return

Most audit selection is not personal and not random. The IRS scores returns against statistical norms and matches them against the information returns third parties already file, then routes the outliers to correspondence, office, or field examination, most of them the milder correspondence kind conducted entirely by mail 1. A small practice is not singled out for being small; it surfaces when a number on its return sits far from the pattern for practices like it, or fails to match a form the agency already holds.

That frame is worth keeping because it lowers the temperature. An examination is, at bottom, a request to explain and document specific lines, conducted with defined taxpayer rights and a defined lookback, usually the last few years 1. The goal of everything below is not to hide from that process but to make it a short conversation you are already prepared for.

The deduction ratios that stand out

The most common flag for a solo practice is a deduction that looks outsized against its income. Every expense must be ordinary and necessary to the practice to be deductible 2, and legitimate ones rarely cause trouble; what draws a second look is a category far above the norm for a practice of your size, or a large one-time write-off with no obvious business story. The deduction is not the problem, the mismatch between the deduction and the documented business reason is.

The usual suspects are predictable: a vehicle claimed as fully business, generous meals and travel, a single large equipment purchase, and continuing losses year after year. A practice reporting losses several years running invites the question of whether it is a business or a hobby, and the answer is documentation of a genuine profit motive, not a smaller deduction. If you spot an error in a prior return while reviewing this, amending it on your own initiative is generally cleaner than waiting for the automated match to find it.

The home-office deduction: legitimate, and frequently misclaimed

The home-office deduction is fully legitimate and, for a telehealth-from-home practice, often correct, but it is also one of the most frequently misclaimed lines on a small-business return. The rule is regular and exclusive use: the space must be used regularly and only for the practice, computed by the simplified method (a set rate per square foot up to a cap) or the actual-expense method 3. A room that doubles as a guest room does not qualify.

The point is not to avoid a deduction you are entitled to, it is to claim it correctly. A dedicated room used only to see patients or do practice work, measured honestly and documented with photos and square footage, is defensible. The same deduction stretched over shared living space is the mismatch that invites review, and it puts an otherwise clean return under a light it did not need.

Worker classification: the 1099 that should have been a W-2

When a practice grows past one clinician, how the new person is paid becomes an audit question. The IRS applies a common-law test, weighing behavioral control, financial control, and the relationship, to decide whether a worker is an employee or an independent contractor 4. Label someone a 1099 contractor while directing their schedule, methods, and tools, and the arrangement can be recharacterized as employment, with back payroll tax, penalties, and interest.

The exposure lands on the practice, not the worker, which is what makes this trigger expensive. It also crosses agencies: a former associate who files for unemployment can prompt a state determination that reaches the IRS. Treating associate clinicians as contractors purely to avoid payroll is the classic misstep. Settle classification against the actual facts of control before you write the first check, and document why the answer is what it is.

Payroll tax deposits: the fastest way to get noticed

Once a practice has even one W-2 employee, including an owner on an S-corp salary, it must withhold and deposit income tax, Social Security, and Medicare on the IRS's schedule 5. Missing those deposits is among the fastest ways to draw enforcement, because the withheld amounts are trust-fund taxes, money the practice holds on behalf of its employees and the government, and a shortfall there is treated far more seriously than a late income-tax payment.

Unpaid trust-fund taxes can be assessed against the responsible person individually, which for a solo practice means the owner, so the liability does not stay behind the entity. The practical defense is unglamorous: calendar the deposit due dates, or hand payroll to a service that makes the deposits and files the returns for you, and never borrow from withheld taxes to cover a slow month. That is the one shortfall that follows you personally.

Underreported income and the document-matching net

The single largest source of flags is income that does not match. The IRS receives copies of the 1099-NEC, 1099-K, and other information returns your payers and card processors file, and its systems compare them against what you reported, generating an automated notice before a human looks 1. The defense is not secrecy; it is substantiation, the contemporaneous records that tie every number on your return to a receipt, statement, or log 6.

Keep those records long enough to matter: generally three years, six years if income was substantially understated, and four years for employment-tax records, and longer when in doubt 6. The substantiation standards are worth knowing before you need them, because in an examination an undocumented but genuine deduction and a fictional one look identical on paper. The reconstructed number you cannot support is the one an examiner disallows, regardless of whether it was real.

Not every audit is the IRS

A solo clinician often braces for the wrong auditor. An IRS examination tests your income and deductions; a payer or Medicare review tests your clinical documentation, and the two run on entirely different rules. Medicare, for instance, requires each service to be authenticated by a handwritten or electronic signature, and a missing signature is cured by attestation, not by a tax receipt 7. Confusing the two wastes preparation, because the records that satisfy one do little for the other.

It helps to keep the audit worlds separate in your head: the IRS looks at taxes, a payer or its recovery contractor looks at whether a billed service was documented and medically necessary, a HIPAA review looks at your safeguards, and your board looks at practice conduct. A payer's overpayment demand or a false-claims question is a different animal with far higher stakes, and the fca and the solo practice is its own subject worth reading separately.

If a letter arrives, and how good books make it a non-event

If a notice does arrive, the worst response is panic and the second worst is silence. Most are correspondence audits or automated under-reporter notices that ask you to explain or document one or two items, with a response deadline printed on the page 1. Read what is actually being asked, gather the substantiation for those specific lines, and answer by the deadline; the irs letter is a request for documents, not a verdict.

Bring in a CPA or tax professional when the letter proposes a large adjustment, escalates to an in-person field audit, or uses referral language, and let them decide whether amending a return or contesting the finding is the better path. An assessment left unanswered can move into collection and, eventually, a levy on the practice account, which is why the printed deadline is the one date to protect. None of this requires living in fear of an audit; it requires books that can answer one, the same discipline that makes every other number in your practice legible.

Common questions

It can when it is claimed without meeting the rule, but a correct claim is defensible. The space must be used regularly and exclusively for the practice, and you can use the simplified per-square-foot method or actual expenses. A dedicated room documented with photos and measurements rarely causes trouble; a shared living area claimed as an office is the mismatch that invites a second look.

Overall audit rates are low, and selection is driven by pattern and mismatch rather than size. What raises a self-employed return's odds is the presence of cash income, large or unusual deductions relative to income, and information returns that do not reconcile with what was reported. A small, clean, well-matched return is not an attractive target; an outlier one is.

An IRS audit examines your income and deductions under the tax code. A payer or Medicare audit examines whether a billed service was documented, coded correctly, and medically necessary, and it can demand repayment. They rely on different records: tax receipts and logs for the IRS, clinical notes and signatures for a payer. Preparing for one does little for the other.

Generally three years from when the return was filed, extended to six years if income was substantially understated, with no limit for a fraudulent return or one that was never filed. Employment-tax records have their own retention period. Keeping your business records at least that long, and longer for anything supporting an asset's basis, is what lets you answer a lookback instead of reconstructing it.

Do not ignore it, and do not overreact. Read exactly which items and years it questions, note the response deadline, and gather the receipts, statements, and logs that substantiate those specific lines. Answer a simple document request yourself; call your CPA before responding to anything proposing a large adjustment, escalating to a field audit, or using referral language. The deadline is the date that matters most.

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References

  1. 1.Internal Revenue Service (2026). IRS audits. Internal Revenue Service. link ✓How the IRS selects and conducts examinations (statistical scoring, information-return matching, correspondence/office/field types, taxpayer rights, and typical lookback), and that most exams are correspondence audits answered by mail.
  2. 2.Internal Revenue Service (2026). Guide to business expense resources. Internal Revenue Service. link ✓The ordinary-and-necessary standard, the frame for why deductions that are outsized against income or poorly documented draw scrutiny.
  3. 3.Internal Revenue Service (2026). Home office deduction. Internal Revenue Service. link ✓The regular-and-exclusive-use requirement and the simplified versus actual-expense methods, the rules a misclaimed home-office deduction fails.
  4. 4.Internal Revenue Service (2026). Independent contractor (self-employed) or employee?. Internal Revenue Service. link ✓The common-law test (behavioral control, financial control, relationship) that governs contractor-versus-employee status, where misclassification exposure falls on the practice.
  5. 5.Internal Revenue Service (2026). Understanding employment taxes. Internal Revenue Service. link ✓That an employer must withhold and deposit income tax, Social Security, and Medicare on the IRS's schedule once it has a W-2 employee, and that withheld amounts are trust-fund taxes treated more seriously than a late income-tax payment.
  6. 6.Internal Revenue Service (2026). Recordkeeping. Internal Revenue Service. link ✓Which records to keep and for how long (generally three years, six for substantial underreporting, four for employment-tax records), the substantiation that answers an audit.
  7. 7.Centers for Medicare & Medicaid Services (2023). Complying with Medicare Signature Requirements. CMS Medicare Learning Network (MLN905364). link ✓That Medicare requires services to be authenticated by signature and that attestation cures a missing signature, illustrating how a payer documentation audit differs from an IRS examination.

https://www.gale.care/for-providers/irs-audit-triggers-practices · 7 sources. Competitor details are cited to dated public sources and maintained as they change; figures are estimates, not commitments. Synthetic demonstration.

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