Preparation and review are different functions. A thoughtful review can catch inconsistencies, missing items, carryovers, elections, and state issues before filing.
In a solo practice
The same experienced professional may prepare and then perform a deliberate self-review using diagnostics, checklists, comparisons, and reasonableness procedures.
In a team practice
A preparer may complete the first draft and a more experienced reviewer may examine it. Ask what the reviewer is expected to check and whether complex issues are escalated.
Software diagnostics are not the whole review
Diagnostics can catch mechanical inconsistencies. They may not recognize that a transaction was classified incorrectly or that a planning opportunity was missed.
Ask about prior-year comparison
Large changes in income, deductions, credits, withholding, and tax can be signals worth investigating before a return is finalized.