8. Deviating from the Norm
The IRS openly admits that a single anomaly on your tax return can result in them auditing you. Sometimes, audits are based solely on a statistical formula that your return had the misfortune of deviating from.
The IRS develops those “norms” from audits of a statistically valid random sample of returns, as part of the National Research Program the IRS conducts.
This means that sometimes, no matter how perfectly you think you have completed your form, the computer system used to analyze it can still pick up something that will cause an audit.