They are not doing your bookkeeping
Unless you have specifically hired them to, a tax preparer is preparing a return from figures you provide. Time spent turning a shoebox into figures is billed, and it is the most expensive possible use of a professional.
The cheapest return is the one where the preparer receives numbers that already add up and spends their time on judgment instead.
What a good handover contains
Not documents. Totals, with the detail available behind them if a question comes up.
- Income by source, reconciled to what actually landed in the bank.
- Expenses totalled by Schedule C line, not by invented category.
- A mileage log with date, miles, destination and purpose per trip.
- The contractors you paid, what you paid them, and their W-9s.
- Any K-1s you have received, and for an S-corp or partnership, your basis.
- Last year’s return, which sets the safe harbor and carries forward anything suspended.
What makes it expensive
A folder of receipts with no totals. Someone has to add them up, and that someone is billing by the hour.
Personal and business in one account with no marking. Separating a year of mixed transactions after the fact is slow and the result is never as accurate as marking them as they happened.
Missing W-9s in January, which turn into a scramble to reach people you no longer work with.
Questions that arrive in April when the answer was obvious in June.
Give them access, not attachments
Email threads with spreadsheet versions attached are how figures get out of step. A single place they can look at, read-only, removes the version problem entirely.
Read-only matters in both directions: they cannot change your records by accident, and you can see what they looked at.