Nobody outside the IRS knows exactly why any single return was chosen — the scoring formulas are not published, and the IRS is not going to hand out a checklist for gaming them. But the selection machinery is not secret. The IRS describes it in its own publications: four selection methods. This page covers those first, plainly labelled, then the patterns practitioners observe in the cases that arrive at their door — labelled as exactly that, and nothing more.
General information, not tax or legal advice. Being selected proves nothing: audits close with no change every day, and selection methods say nothing about whether your return is wrong.
1. Computer scoring — the DIF system. Most individual returns are scored by a computer program called the Discriminant Information Function (DIF), which compares the entries on your return against statistical norms built from prior audits of similar returns. The score rates the potential for change — how likely an exam is to produce additional tax. The IRS does not publish the formula or its weights, and no one outside the IRS knows your score.
2. Document matching. Employers, banks, brokers and platforms report your income to the IRS on W-2s and 1099s, and the IRS matches those reports against your return. A mismatch — income reported to the IRS that never made it onto your return — draws contact. In practice, most mismatches produce a CP2000 notice from the automated underreporter programme — a proposed adjustment, not an audit — rather than an examination.
3. Related examinations. When the IRS audits a business, it may pull the returns of the people connected to it: partners, shareholders, investors, employees with related transactions. Your return can be selected because someone else’s was — no flag on your own return required.
4. Random selection. Some returns are chosen purely by statistical formula, to measure compliance and recalibrate the scoring systems. There is no defence and no signal in being picked this way; it is the tax system’s equivalent of a quality-control sample.
Announced enforcement initiatives (not a fifth method). Separately from the four methods, the IRS publicly announces enforcement focuses in its news releases — announced examples include Employee Retention Credit claim reviews and campaigns aimed at high-income and partnership compliance. An announced initiative is a resource decision, not a personal trigger: it is not a selection method, and it does not mean any individual return inside the area was flagged.
Coverage, with its date attached. Audit statistics are only meaningful with their source and year: the IRS examined roughly 0.2% of individual returns for tax year 2022 (IRS Data Book figure). Coverage rises materially with income and for certain return types, and the figures are snapshots that rise as examinations close — context for scale, never a statement of your personal odds.
The DIF formula, its weights, and any threshold score. No complete trigger list exists outside the IRS, and the Service does not publish one. That vacuum fills with folklore every filing season: that filing an extension invites an audit, that filing on paper (or electronically) changes your odds, that amending a return guarantees examination. The IRS has never confirmed these claims, and none of them appears in its description of how selection works. Treat any article presenting them as established fact — or selling you the “real” list — as entertainment, not information.
Tax practitioners who handle audits see the same return features repeatedly in the cases that land on their desks. These are practitioner consensus, not IRS-published criteria — each is also claimed by honest filers every day, and none is evidence of anything by itself:
The practical use of this list is not prediction — it is preparation. If your return carries one of these features legitimately, the record-keeping checklist is what turns a selection into a no-change closing letter. And remember the window: almost all of this operates inside the 3-year (sometimes 6-year) audit period.
What triggers an IRS audit? Selection, by the IRS’s own account, happens four ways: computer scoring (the DIF system), document matching against W-2s and 1099s, related examinations of connected taxpayers, and random selection. Beyond those published methods, the IRS releases no trigger list — the “red flags” in most articles are practitioner consensus about patterns that score badly, not IRS criteria.
What is a DIF score? The Discriminant Information Function score: the IRS computer’s rating of a return’s potential for change, based on norms drawn from prior audits of similar returns. A high score means the return sits far from those norms — it is an estimate of audit potential, not a finding that anything is wrong. The IRS does not publish the formula, and no one outside the IRS knows your score.
Can claiming the home office deduction trigger an audit? There is no IRS-published trigger list to appear on — the IRS has never named the home office deduction, or any single deduction, as a selection criterion. It appears on practitioner red-flag lists only as part of a pattern: deductions grossly disproportionate to the income reported. A home-office claim that fits your income profile and is documented (see the record-keeping checklist) is an ordinary deduction, not a flag by anything the IRS has published.
Does the IRS audit random returns, or only flagged ones? Both. Random selection is one of the IRS’s own published methods — some returns are picked purely by statistical formula, with nothing flagged at all, to measure compliance and calibrate the scoring systems. Most selections, though, come from DIF scoring, document matching or a related examination.
Sources: IRS, “IRS audits” and examination-selection material (irs.gov); practitioner red-flag patterns are labelled in the text as practitioner consensus — the IRS publishes no red-flag list and no DIF formula; the one coverage figure quoted is the IRS Data Book figure for tax year 2022, labelled as such in the text. Currency verified 2026-10-23.