Most people hire a CPA too late, after a problem has already happened, or never at all, because tax software works fine right up until it doesn't. Here's an honest framework, from a CPA who pays another CPA to do his taxes.
When software is genuinely fine
One clean W-2, the standard deduction or a straightforward set of itemized deductions, no business income, no rental property, no significant investment complexity. Software handles this well and cheaply. Paying a CPA here mostly buys convenience and peace of mind, not a materially better outcome.
The triggers that change the math
Each of the following adds either genuine tax-code complexity, real dollars at stake, or both:
- Self-employment or 1099 income, even a modest side amount
- Running a business, including a small one, with real expenses and deductions to track
- Owning rental property
- Equity compensation: RSUs, stock options, or ISOs, which carry timing and tax elections that are easy to get wrong
- Income earned in more than 1 state in the same year
- A major life event with tax consequences: marriage, a home sale, an inheritance
- Simply owing enough that a mistake would be expensive to fix
A CPA's fee is usually a fixed, known cost. A missed deduction, or a mistake that draws attention from the IRS, is not, and the second one is a far worse number to find out about later.
What a CPA actually does that software doesn't
A good CPA isn't just filling in the same boxes faster than you would. The real value is planning ahead of year-end, entity structure, retirement contribution timing, when to recognize income or expenses, rather than just reporting what already happened after the fact. Software is backward-looking by design. A CPA relationship, done right, is forward-looking.
How to think about the cost
Treat it like any other business decision: compare the fee to the expected value of the deductions captured, penalties avoided, or errors prevented, plus the value of the hours it frees up for you. For a straightforward personal return, software is the right call. For a small business or anything on the trigger list above, it usually makes sense to have a CPA take a look.
Software is fine until your situation has genuine complexity or real money at stake. Once either shows up, hire a CPA, not primarily to file the return, but to plan around it before the year is already over and the decisions are already made.