Four kinds of errors keep reaching review at CPA firms, and none of them are arithmetic. A carryforward that doesn't match what was actually filed. An accounting method that changed without the form that authorizes changing it. A schedule total that disagrees with the document behind it. A position taken with no record of whether it needed to be disclosed. Each one is preventable in principle and recurring in practice, and the reason is the same reason across all four: the fact that would have caught it never made it into the return in the first place.
That distinction matters more than it sounds. A reviewer catching a typo is the review process working as designed — cheap to find, cheap to fix. A reviewer catching one of these four is the review process working as a backstop for something that should have been settled earlier, by someone else, on paper. The cost of that backstop is real, and it recurs every season for a structural reason a stricter checklist doesn't fix.
Four errors, and why each one survives preparation
Each one traces back to the same gap: a fact the review depends on that never made it into the return itself.
Carryforward mismatches
The balance in the software and the balance on the return as actually filed quietly diverge — an IRS adjustment, an amendment, or an out-of-system fix breaks the link, and nothing reconciles the two until a reviewer checks.
Elections without their own paperwork
A method change already shows up in the current return, but its authorization lives in a memo or email thread, not attached to the line it affects — often with no Form 3115 anywhere in the file.
Source disagreement
A K-1 basis or a 1099 total that doesn't tie to its source document. The figure is trusted the moment it enters the software, and nothing re-traces it back unless a reviewer decides to.
Disclosure gaps
A position is taken with no record of whether it clears the authority standard or needs Form 8275 — the decision 31 CFR § 10.34 requires, backstopped by IRC § 6662's 20-percent penalty on an unsupported position.
None of these four is a mistake in arithmetic. Each is a fact that was true somewhere the return itself couldn't see it.
Why review catches them late, and not earlier
Each of these four maps onto one of the checks a thorough review is already built around — continuity against the prior-year return, agreement between the return and its own source documents, the authority standing behind a position. A reviewer working through that sequence will eventually find most of them. "Eventually" is the problem. By the time a continuity failure or a source disagreement surfaces in review, the preparer who could resolve it fastest is usually two clients further into their own queue, and the return goes back into a batch instead of forward toward filing.
The five checks these errors fall under
See Pernee's complete guide to tax return review — the checks these four error types map onto, and where each one is designed to catch them.
What would keep them from reaching review at all
The fix isn't a longer checklist item for each of the four — firms already have checklists, and a checklist can only ask a preparer to remember something that lives somewhere else. What's missing in each case is the same thing: the supporting fact — last year's actual filed balance, the election memo, the source document, the disclosure decision — attached to the return line it explains, at the moment the return line is created, instead of reconstructed later by whoever happens to be reviewing.
Pernee attaches that record to the return itself as the return is built, so a reviewer isn't the first person checking whether a carryforward matches, an election has its 3115, or a position's disclosure question got asked. The check still gets made. It just doesn't have to wait for someone to notice it wasn't.
Give the review the record it's currently missing
See how Pernee keeps carryforwards, elections and disclosure decisions attached to the return line they explain, before a reviewer ever has to go looking.
