Most tax returns have errors. The government counted.
When federal investigators went undercover to paid tax preparers, almost nobody got the refund exactly right. IRS research data tells the same story at scale. If your return was prepared in a hurry, the error may still be sitting in it — costing you money now, or waiting to cost you more later.
What the studies found
Each study below was run by the government, not by a software company. Returns were checked against the filers' own documents — the only way errors actually surface.
Paid preparers in undercover GAO visits who calculated the correct refund amount. The rest were off by anywhere from $52 under to $3,718 over the correct refund.
Estimated share of preparer-filed returns containing an error that changed the tax or the refund. Self-prepared returns came in at about 50%.
Mistakes flagged by the IRS in math-error notices for tax year 2023 alone — more than a million taxpayers received a notice changing their return.
Where returns go wrong
The errors that change what you owe are rarely exotic. They are the everyday items a rushed preparation misses:
Income left off
Cash tips, side income, and business income that never made it onto the return — the single most common error investigators found.
Credits claimed wrong
Earned Income and education credits claimed for ineligible dependents, or without the eligibility checks the law requires.
Deductions & elections missed
An election never filed, a limitation applied the wrong way, a deduction simply overlooked — each one raises the tax.
Carryforwards dropped
Losses, credits, and basis figures from prior years that never carried into the current return.
Cost basis errors
A mis-entered basis on an asset sale overstates the gain — and overtaxes money you already paid tax on once.
Math & mismatches
Figures that do not tie between forms. The IRS flagged over 1.2 million of these for tax year 2023.
The Second Look Review
TaxWizardUSA re-checks your filed return line by line against your original documents — the same re-preparation method investigators used, applied to your return. Every review ends in one of three outcomes:
Your return is right
You receive written confirmation that the return ties to your documents. Peace of mind, documented.
The error is in your favor
You overpaid. We prepare Form 1040-X to amend the return and claim your refund — generally available within 3 years of the original filing deadline.
The error runs against you
Better corrected on your terms. An amendment now usually costs less than an IRS notice later — and a math-error adjustment becomes final if it is not challenged within 60 days.
Send your return & documents
Your filed return plus the documents it was prepared from — W-2s, 1099s, statements, prior-year return.
Line-by-line review
Every figure on the return is traced back to its source document and recomputed.
Written findings
Clean, amendment recommended, or correction needed — with the figures shown, so you can see exactly what changed and why.
Find out which kind of return you filed.
If your refund was calculated by whoever had capacity that week, it is worth a second look — especially with an amendment window that closes.
Request Your Review (954) 352-3927Sources. U.S. Government Accountability Office, Paid Tax Return Preparers: In a Limited Study, Preparers Made Significant Errors (GAO-14-467T, April 2014), including undercover site visits to 19 preparers and analysis of IRS National Research Program data for tax years 2006–2009. IRS math-error figures for tax year 2023 as reported from IRS data (more than 1 million notices covering over 1.2 million mistakes). The GAO sample was limited and cannot be generalized to any individual preparer or return. These statistics describe studies of returns prepared by others; a Second Look Review examines your return on its own facts and cannot guarantee a refund or any specific outcome. Amendment deadlines vary by situation — ask us about yours.