A good CPA does more than file an accurate return -- they ask questions, explain changes, and tell you things you did not know to ask about. You can evaluate the quality of the work after the fact by checking a specific set of behaviors against the professional standards that govern their practice. If your CPA hit most of the green flags below and none of the red ones, you are probably in good hands. If the red flags outnumber the green, it is time to start looking.
Pull out your most recent tax return before working through this checklist. You will need to check the "Paid Preparer Use Only" section on page 2 of your 1040, review any year-over-year changes your CPA flagged, and confirm that carryforward items from prior years were picked up correctly.
Work through this list with your most recent return in front of you. A strong CPA engagement will check most or all of these boxes.
They Asked About Life Changes
Before touching a single form, your CPA should have asked what changed in your life during the tax year. Marriage, divorce, a new child, a job change, buying or selling a home, starting a business, retirement, an inheritance -- each of these triggers specific tax consequences that cannot be discovered by staring at a W-2.
This is not optional courtesy. AICPA Statement on Standards for Tax Services (SSTS) No. 2 requires members to "make reasonable inquiries if the information furnished appears to be incorrect, incomplete, or inconsistent." A CPA who files your return without asking about life changes is skipping a step their own professional standards require.
They Reviewed Prior-Year Carryforwards
Your tax return does not exist in isolation. Items carry forward from year to year, and a competent CPA tracks them:
- Capital loss carryforwards -- if you had net capital losses exceeding $3,000 last year, the unused portion should appear on this year's Schedule D
- Net operating losses (NOLs) -- post-2017 NOLs carry forward indefinitely but can only offset up to 80% of taxable income
- Passive activity losses -- suspended losses from rental properties or limited partnerships that could not be deducted in prior years
- Charitable contribution carryovers -- donations exceeding the AGI percentage limits carry forward for up to five years
- State and local tax (SALT) refunds -- if you itemized last year, a state refund may be taxable income this year
Technical detail
They Explained What Changed From Last Year
A brief year-over-year summary is one of the clearest signals of a thorough engagement. Your CPA should be able to tell you -- in plain language -- why your refund or balance due shifted, which line items moved materially, and whether any of those changes were one-time events or trends that will continue.
This does not need to be a formal report. Even a two-paragraph email or a five-minute conversation at the end of the appointment counts. What matters is that the CPA looked at the overall picture, not just the current-year numbers.
They Discussed Planning Opportunities
Tax preparation is backward-looking. Tax planning is forward-looking. A CPA who only does the first is providing half the service.
After reviewing your return, a good CPA will raise at least one or two ideas for next year:
- Adjusting withholding or estimated payments to avoid a surprise
- Retirement contribution strategy changes (Roth conversion timing, catch-up contributions)
- Timing capital gains or losses
- Entity structure considerations if you are self-employed
- Bunching charitable contributions in alternating years to clear the standard deduction threshold
If your CPA finished the return and said nothing about the future, they may be a compliance-focused preparer rather than an advisory-oriented professional.
They Filed on Time (or Communicated About Extensions)
This one is straightforward. If you provided your documents with reasonable lead time and your return was filed by the April deadline -- or an extension was filed with a clear explanation of why and what comes next -- your CPA met the baseline expectation.
If the extension was filed because the CPA was overloaded and never communicated a timeline, that is a different story.
They Responded to Questions
You should be able to ask your CPA a reasonable question about your return and get a substantive answer within a few business days. "Why is line 23 different from last year?" is not an unreasonable question, and "that's just how the software calculated it" is not an acceptable answer.
Under IRS Circular 230 Section 10.33, practitioners are expected to exercise due diligence and competence, which includes the ability to explain their own work product.
They Signed the Return and Included Their PTIN
Every paid preparer is required by law to sign the return and include their Preparer Tax Identification Number (PTIN). Under IRC Section 6695, the penalty for failing to sign is $50 per return, and the penalty for omitting the PTIN is another $50 per return. More importantly, a preparer who does not sign the return is signaling that they do not want to stand behind their work. That should concern you.
Check the bottom of page 2 of your Form 1040. If the "Paid Preparer Use Only" section is blank, ask why.
Any single red flag might have an innocent explanation. Two or more together suggest a pattern.
No Year-Over-Year Comparison
If your CPA never mentioned how this year compared to last year, they probably did not look. A return prepared in isolation -- without reference to prior years -- is more likely to miss carryforwards, catch errors in income reporting, or overlook trends that signal planning opportunities.
They Did Not Ask About Changes in Your Life
This is the mirror image of the first green flag, and it is the most telling red flag. A CPA who files your return based solely on the documents you provided, without asking a single clarifying question, is treating your return like a data-entry exercise. AICPA SSTS No. 2 explicitly requires reasonable inquiry. No questions means the standard was not met.
They Just Entered Numbers Without Advisory
If the entire engagement consisted of you sending documents and receiving a return -- no conversation, no questions, no planning suggestions, no explanation of changes -- you received a commodity service at a professional price. That does not mean the return is wrong, but it means you are not getting the value that distinguishes a CPA from tax software.
For context, the average CPA fee for a base 1040 is $280. If all you got was data entry, you overpaid relative to what software or a non-credentialed preparer would charge.
Errors on Basic Items
Errors happen, but some errors are harder to excuse than others:
- Wrong filing status -- the IRS flags this immediately, and the rules are unambiguous
- Missing income -- if a 1099 or W-2 was provided and does not appear on the return, that is a matching notice waiting to happen
- Math errors -- professional software handles arithmetic, so a math error on a CPA-prepared return usually means manual overrides gone wrong
- Incorrect Social Security numbers -- the IRS rejects these outright, and your CPA should be verifying them against source documents
- Missing required forms -- if you have a foreign bank account and no FBAR was discussed, or you sold a rental property and there is no Form 4797, something was overlooked
Technical detail
They Could Not Explain Deductions
Ask your CPA to walk you through two or three of the larger deductions on your return. A CPA who prepared the return should be able to explain, without referencing notes, what each deduction represents and why you qualify. If they cannot, they may not have evaluated the deductions themselves -- which raises questions about whether the positions on your return have the "reasonable basis" required by IRS Circular 230 Section 10.34.
They Did Not Discuss Estimated Payments
If your return shows a balance due (or a large refund), your CPA should proactively address whether your withholding or estimated payments need adjustment for next year. Ignoring this leaves you exposed to the same surprise next April -- plus potential underpayment penalties under IRC Section 6654.
The Scoring: Where Do You Stand?
Count your green flags and red flags from the lists above.
- No year-over-year comparison or life-change questions
- Return prepared as a data-entry exercise with no advisory
- Errors on basic items like filing status, missing income, or wrong SSNs
- Could not explain deductions or planning opportunities when asked
- No discussion of estimated payments despite a balance due or large refund
- Asked about life changes before touching any forms
- Reviewed and applied all carryforwards from prior years
- Provided a year-over-year summary explaining what changed and why
- Raised forward-looking planning ideas after completing the return
- Filed on time (or communicated clearly about the extension) and responded to questions promptly
Switching CPAs is inconvenient, which is why most people tolerate mediocre service longer than they should. But the cost of a bad CPA compounds: missed deductions accumulate, planning opportunities pass, and errors create IRS correspondence that eats your time for months.
Consider making a change if:
- You found multiple red flags above -- the checklist results speak for themselves
- Your situation has outgrown your CPA's expertise -- a generalist who was fine for your W-2 return may not be equipped for your new rental properties or S-Corp
- You cannot get timely responses -- if routine questions take weeks to answer, your CPA is either overloaded or disengaged, and neither serves you well
- Fees keep rising without added value -- annual increases are normal, but 15-20% jumps with no new services suggest you are subsidizing the firm's overhead
- They are reactive, never proactive -- a CPA who only contacts you when they need documents is a filing service, not an advisor
The IRS holds you -- not your CPA -- responsible for the accuracy of your return. You signed it. If your CPA made errors that resulted in penalties, you may have a claim against them, but the IRS will collect from you first. This is why evaluating your CPA's work matters: catching problems early costs far less than cleaning up IRS notices after the fact.
Not all CPAs are interchangeable. When evaluating a new CPA, prioritize:
- Specialization in your situation -- ask what percentage of their clients look like you. A CPA who primarily serves small businesses may not be the right fit if your complexity comes from rental properties or stock compensation.
- A structured intake process -- a CPA who sends a detailed questionnaire or organizer before your first meeting is demonstrating the kind of thoroughness you want applied to your return. Compare this to a CPA who just asks you to "send over your documents."
- Year-round availability -- if you need planning advice in October, will they be there? Or do they only surface in January?
- Clear pricing -- get the fee structure in writing before engaging. Understand what is included and what triggers additional charges.
- Credentials you can verify -- every CPA holds a state license, and every paid preparer should have a PTIN. The IRS Directory of Federal Tax Return Preparers lets you search by name, zip code, or credential type. Your state board of accountancy maintains license status and disciplinary history.
- Willingness to explain -- during your initial consultation, ask a specific tax question about your situation. How they answer tells you more than their credentials do. A good CPA explains clearly. A mediocre one deflects or recites jargon.
For more detail on the differences between CPAs, Enrolled Agents, and other preparers, see our comparison guide and situation-based matching guide.