Tax software can perform arithmetic with remarkable accuracy. The harder problem is deciding what the facts mean, where they belong, and whether a question is asking what you think it is asking.
Software depends on the facts you give it
If income is omitted, basis is wrong, a prior-year carryforward is missing, or an asset is classified incorrectly, the software can calculate the wrong result perfectly.
Interview questions use tax concepts, not always ordinary English
A taxpayer may read “foreign-source income,” “material participation,” “basis,” “business use,” “dependent,” or “active trade or business” in an everyday sense. Tax law may use those terms more narrowly or more technically.
The software may not know what you forgot
If you never tell the program about a prior passive-loss carryforward, an inherited basis issue, a nondeductible IRA contribution, an entity election, or a state move, it may never ask the question that would expose the missing fact.
Classification can be more important than calculation
Is a payment wages, self-employment income, rental income, a capital transaction, or something else? Is an expenditure a current deduction, inventory, a capital asset, or an improvement? The classification drives the tax treatment.
Elections and deadlines may not be obvious
Some tax outcomes depend on elections, statements, accounting methods, entity filings, or deadlines. A guided interview may not communicate the strategic importance of choosing one treatment over another.
State taxation can multiply complexity
Moving during the year, working remotely, owning a business in another state, receiving K-1s, or having rental property across state lines can create allocation, residency, credit, and filing issues beyond the federal return.
Business owners face interconnected returns
An S corporation return, shareholder basis, reasonable compensation, health insurance, retirement contributions, accountable-plan reimbursements, and the individual return interact. Preparing one piece without understanding the others can produce errors that software cannot diagnose from a single interview.
The final return needs a reasonableness check
One of the most valuable professional questions is simply: “Does this result make sense?” A refund or balance due that differs sharply from expectations deserves investigation before filing.