The problem with his case was that he had prepared the return and the deficiency was from a math error.

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Update if I correct for my math error, then the bearish estimate gave a 700 point downside to the Dow.

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Cognitive errors, such as a math error, result from faulty reasoning and can often be corrected once the client is made aware of the error.

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"Math error doesn't work for fact and circumstance" situations.

WSJ: Lawmakers Consider Expanding IRS Power to Flag Errors Before Audits

"Math error works for clean issues, " she said Wednesday.

WSJ: Lawmakers Consider Expanding IRS Power to Flag Errors Before Audits

Don't panic if you accidentally put too much into an IRA (say because you made a math error and the IRS calculated your refund as bigger.) You have until Oct. 15 to fix it by taking out the excess.

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Another 7.5 million filers think they're done, but are going to hear otherwise from the IRS. This includes 3 million who will receive "math error" letters telling them they've made some computational or other mistake, and 3 million who will get "automated underreporter" notices stating they appear to have left off income reported to the IRS by a third party.

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The tax agency's power to use math-error authority historically has been fairly limited.

WSJ: Lawmakers Consider Expanding IRS Power to Flag Errors Before Audits

Steven Miller, the IRS deputy commissioner for services and enforcement, declined to specifically request expanded math-error authority for his agency.

WSJ: Lawmakers Consider Expanding IRS Power to Flag Errors Before Audits

Scholars at the American Enterprise Institute examined what happens to the Tax Policy Center math when this error is corrected.

WSJ: Review & Outlook: Mathematically Possible