CPA firms
AI for U.S. CPA firms: keep SSNs and ITINs out of ChatGPT
Prep returns and answer client emails at your CPA firm with ChatGPT, Claude or Copilot. SSNs, ITINs and EINs are redacted before the paste.
No sign-up, no card · Installs in a minute
One tool for the whole tax season
Organizer notes, client emails, workpapers and IDs: Nonimo redacts taxpayer identifiers on every preparer's machine.
Nonimo in the center redacting made-up prep notes, with four uses around it: one key on the notes in any app, ChatGPT, Claude and Gemini through the Chrome and Safari extension, workpapers and spreadsheets, and a new client's passport.
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Highlight the prep notes, press the key and the taxpayer becomes [PERSON_1] before you paste.
See it in an email → -
W-2s in PDF, engagement letters in Word, trial balances in Excel: redacted before the upload.
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ChatGPT, Claude or Gemini: the Chrome and Safari extension redacts it, alongside your Windows or Mac app.
Try the extension → -
Black out what the ID check doesn't need and watermark the license with your firm and tax year.
Redact a license → -
When your company’s apps call an AI model through the API, Nonimo Gateway swaps out client details on your own servers before each request leaves.
See the Gateway →
[nonimo]
Email · Outlook
Your original
Ms. Lorna Fessendrake still owes us her 1099-B for File No. TX-2026-0418.
Sent to the AI
Ms. [PERSON_1] still owes us her 1099-B for File No. [REFERENCE_1].
organizer.xlsx · row 31
Your original
Client: Ewan Marchbristle · Phone: (720) 555-0146 · SSN: 000-00-0042
Sent to the AI
Client: [PERSON_1] · Phone: [PHONE_1] · SSN: [REFERENCE_1]
Nonimo Gateway
Your original
Draft a reply to Trevor Ashgrove at t.ashgrove@example.com about his billing dispute.
Sent to the AI
Draft a reply to [PERSON_1] at [EMAIL_1] about his billing dispute.
Passport · photo page
The AI never sees your dataReversibleNo cloud involved
Ask about the return, not the taxpayer
The AI only sees labels. Your client's numbers return to the email on your machine, ready for the portal.
Using the extension in ChatGPT, Claude or Gemini, a preparer asks for a missing items list, an engagement letter or an extension notice for a made-up client, with an email or phone and a file number. The AI only ever sees labels in their place. Clicking once puts the client's real details back into the reply, and the panel below previews the email the client will receive. With the key, from Outlook or Word: a client's email is redacted, pasted into an AI assistant, and the reply is copied back with the client's numbers on the next press.
Write a short list of what we still need for the 2025 Form 1040: brokerage 1099-B and the daycare receipts. Client: Ottilie Brashwend[PERSON_1] Email: o.brashwend@example.net[EMAIL_1] File No.: TX-2026-0533[REFERENCE_1]
To: o.brashwend@example.net[EMAIL_1] Subject: Your 2025 return, file TX-2026-0533[REFERENCE_1] Hi Ottilie Brashwend[PERSON_1], to finish your return we still need two things: the 1099-B from your brokerage and the daycare receipts for the dependent care credit.
To: o.brashwend@example.net[EMAIL_1] Subject: Your 2025 return, file TX-2026-0533[REFERENCE_1] Hi Ottilie Brashwend[PERSON_1], to finish your return we still need two things: the 1099-B from your brokerage and the daycare receipts for the dependent care credit.
Names and numbers restored, ready for the portal.Draft the opening paragraph of an engagement letter for a Schedule C client. Client: Ewan Marchbristle[PERSON_1] Phone: (720) 555-0146[PHONE_1] File No.: TX-2026-0592[REFERENCE_1]
Engagement letter · file TX-2026-0592[REFERENCE_1] Dear Ewan Marchbristle[PERSON_1], this letter confirms that we will prepare your 2025 federal and state income tax returns, including Schedule C. Questions are welcome at any time, and we will phone you at (720) 555-0146[PHONE_1] before we file.
Engagement letter · file TX-2026-0592[REFERENCE_1] Dear Ewan Marchbristle[PERSON_1], this letter confirms that we will prepare your 2025 federal and state income tax returns, including Schedule C. Questions are welcome at any time, and we will phone you at (720) 555-0146[PHONE_1] before we file.
Names and numbers restored, ready for the portal.Tell the client we filed an extension and what that does and does not cover. Client: Cassius Wendlethorne[PERSON_1] Email: c.wendlethorne@example.com[EMAIL_1] File No.: TX-2026-0617[REFERENCE_1]
To: c.wendlethorne@example.com[EMAIL_1] Hi Cassius Wendlethorne[PERSON_1], we filed an extension on file TX-2026-0617[REFERENCE_1], so your return is now due October 15. An extension gives you more time to file, not to pay, so any balance was still due April 15.
To: c.wendlethorne@example.com[EMAIL_1] Hi Cassius Wendlethorne[PERSON_1], we filed an extension on file TX-2026-0617[REFERENCE_1], so your return is now due October 15. An extension gives you more time to file, not to pay, so any balance was still due April 15.
Names and numbers restored, ready for the portal.Write a short list of what we still need for the 2025 Form 1040: brokerage 1099-B and the daycare receipts. Client: Ottilie Brashwend[PERSON_1] Email: o.brashwend@example.net[EMAIL_1] File No.: TX-2026-0533[REFERENCE_1]
Draft the opening paragraph of an engagement letter for a Schedule C client. Client: Ewan Marchbristle[PERSON_1] Phone: (720) 555-0146[PHONE_1] File No.: TX-2026-0592[REFERENCE_1]
Tell the client we filed an extension and what that does and does not cover. Client: Cassius Wendlethorne[PERSON_1] Email: c.wendlethorne@example.com[EMAIL_1] File No.: TX-2026-0617[REFERENCE_1]
Hi, I just got a corrected 1099-DIV. Does that change anything on File No. TX-2026-0418[REFERENCE_1]? Best number is (720) 555-0173[PHONE_1]. Thanks, Lorna Fessendrake[PERSON_1]
Hi, I just got a corrected 1099-DIV. Does that change anything on File No. TX-2026-0418[REFERENCE_1]? Best number is (720) 555-0173[PHONE_1]. Thanks, Lorna Fessendrake[PERSON_1]
Hi Lorna Fessendrake[PERSON_1], Thanks for sending it. We'll update TX-2026-0418[REFERENCE_1] with the corrected 1099-DIV before we file, and if the numbers move, we'll call you at (720) 555-0173[PHONE_1].
Hi Lorna Fessendrake[PERSON_1], Thanks for sending it. We'll update TX-2026-0418[REFERENCE_1] with the corrected 1099-DIV before we file, and if the numbers move, we'll call you at (720) 555-0173[PHONE_1].
Names and numbers restored, ready for the portal.The 1040 notes, before and after one keypress
The client's name, SSN, ITIN, EIN and routing number are redacted. The question about what's still missing comes through intact.
Before: what gets pasted
List what is still missing for this return. 2025 Form 1040, married filing jointly Client: Jane Doe Taxpayer SSN 000-00-0001 Spouse ITIN 970-00-0001 Schedule C business, employer identification number 00-0000001 Refund by direct deposit, ABA routing number 130000006
After: what the AI receives
List what is still missing for this return. 2025 Form 1040, married filing jointly Client: [PERSON_1] Taxpayer SSN [REFERENCE_1] Spouse ITIN [REFERENCE_2] Schedule C business, employer identification number [REFERENCE_3] Refund by direct deposit, ABA routing number [REFERENCE_4]
The question the Journal of Accountancy asks first
Before any paste: is this confidential client information? When the answer is yes, Nonimo redacts the taxpayer's numbers on the preparer's computer.
For every preparer in the firm
Set it up before the season starts, beginning with whoever already asks ChatGPT about returns.
One preparer in a minute
Set up the app on a single Mac or Windows machine and run it on prep notes you invent.
The whole firm in one go
IT rolls out the extension by policy, and pastes into ChatGPT or Claude come out redacted on their own.
Easy for your Qualified Individual
Your Qualified Individual can walk through every redacted category before January.
The detail for CPA firms
What prep notes carry, the AICPA confidentiality rule, section 7216, and getting set up before the season.
The AICPA client confidentiality rule and the prep notes: what they carry
The AICPA client confidentiality rule follows what a preparer pastes into ChatGPT: organizer notes for a missing items list, a W-2 to check against last year’s, the email to a client who still owes you 1099s, the reminder that a Form 8879 is waiting for a signature before you can e-file, a Schedule K-1 the client wants explained in plain English. When a new client has to send a passport to prove identity, ask for a watermarked passport copy that names your firm and the tax year; a permanent resident can send a watermarked Green Card copy instead. If you need a copy of a client’s or a dependent’s Social Security card for the file, ask for a Social Security card with a watermark naming your firm and the tax year.
Each one carries the numbers tying a client to the IRS and the bank: SSN, ITIN, EIN, routing and account numbers. The rule’s formal name is the Confidential Client Information Rule, ET sec. 1.700.001, and in August 2026 the Journal of Accountancy applied it to AI tools, noting that CPAs in public practice carry it as an added layer on top of everyone else’s duties. How redaction plays for accountants is covered in our guide on redaction before AI.
The person who answers for this is the Qualified Individual the FTC Safeguards Rule requires the firm to designate, and in a small firm that is usually the managing partner. The rule treats a tax preparer as a financial institution and expects a written information security program in place before the season starts, which in practice means before the first return is touched each January.
What ChatGPT gets from the prep notes after the key
Here is how AI for CPA firms works with the taxpayer left out: the preparer highlights the notes, presses one key, and ChatGPT, Claude or Copilot gets placeholders where the SSN and ITIN were.
On that machine, the client’s identifiers turn into placeholders before the text goes to the chat. More on our security page.
Nothing is hidden from you: every redacted detail is highlighted on screen, and one click brings it back. The real numbers go back into the AI’s answer on the preparer’s machine, ready to check against the file.
In the example, the SSN, the spouse’s ITIN, the business’s employer identification number and the routing number for the refund all became placeholders, and so did the client’s name. Read the after panel as you would a draft return before signature.
What the AICPA confidentiality rule and section 7216 ask of the firm
The AICPA confidentiality rule, as it meets AI, comes down to one question before pasting: is this confidential client information? The firm answers it; when the answer is yes, one key redacts the SSN, the ITIN and the other identifiers before the paste.
For return information there is a statute behind the ethics rule. Section 7216 of the Internal Revenue Code makes it a misdemeanor for a preparer to knowingly or recklessly disclose information furnished for a return: up to a year in prison, a fine of up to $1,000 ($100,000 where section 6713(b) applies), or both. Disclosures under Treasury regulations, or with the taxpayer’s consent, are carved out.
A bylined column in the Journal of Accountancy on July 1, 2026, written for the AICPA’s journal rather than issued by the AICPA, tells CPAs to learn “how and where information provided to each AI tool is stored, who has access to the information, whether the information is de-identified, and whether the information is used to feed and further train the tool.” Our ChatGPT data guide answers that for OpenAI.
The IRS has a template for writing that down. Publication 5708 (Rev. 8-2024), the sample written information security plan the IRS and its Security Summit partners prepared for tax and accounting practices, includes Sample Attachment B, rules of behavior for safeguarding client PII that every user signs. A sentence on AI belongs there: which tools are approved, and that taxpayer identifiers come out before anything is pasted.
Client confidentiality at the CPA firm: price and getting started
Among AI tools for CPA firms, Nonimo installs preparer by preparer, on Windows or on a Mac, and the best time is before the season, alongside the written program.
The installers for both systems are in the buttons at the top of this page, one for each preparer’s computer.
Firm-wide, IT deploys a browser extension by policy that redacts text automatically in the AI tools, without a keypress, before the text is sent. In your written program, describe the app as a redaction step on each preparer’s computer. The Qualified Individual the Safeguards Rule asks the firm to designate is the person to sign off on that description.
Questions from CPA firms
Does the AICPA client confidentiality rule allow our staff to put client returns into ChatGPT?
Only after answering the question the AICPA's own journal puts first: is this confidential client information? If it is return information, section 7216 of the Internal Revenue Code applies as well, together with its carve-out for disclosures the taxpayer consents to. That call is the firm's; once you have made it, the key changes what actually reaches the AI, starting with the SSN and ITIN.
Does a signed section 7216 consent cover pasting a return into an AI tool?
Don't assume it does. Under 26 CFR 301.7216-3 the consent is signed and dated, names the purpose, the specific recipients and the specific return information, and a use and a disclosure each need their own document. The same section also says a 1040 filer's SSN going to a preparer outside the United States has to be masked unless IRS-defined safeguards are in place. Whether your form reaches an AI vendor is a question for your counsel; redacting the SSN first narrows it.
Does pasting a return into ChatGPT violate section 7216?
Not automatically. Section 7216 makes it a misdemeanor for a preparer to disclose return information knowingly or recklessly, with up to a year in prison, a fine of up to $1,000, or both, and it carves out disclosures under Treasury regulations or with the taxpayer's consent. Whether a disclosure is lawful turns on section 7216; Nonimo cuts down how much of the taxpayer reaches the AI in the first place.
Does Nonimo belong in our written information security program?
It can, as long as the description is accurate. The FTC Safeguards Rule, 16 CFR Part 314, requires every tax preparer to keep a written information security program, and firms holding information on 5,000 or more consumers also need a written risk assessment and incident response plan. The IRS sample plan for small practices, Publication 5708, includes sample rules of behavior for staff, and that is where a line on AI fits. Describe Nonimo as it is: a redaction tool on each workstation that the preparer triggers with a key.
We keep the books for a medical practice. Can HIPAA reach a CPA firm?
It can. In August 2025 the HHS Office for Civil Rights settled a HIPAA Security Rule investigation with BST & Co. CPAs, a New York firm that receives financial information containing patients' health information from a health care client, after a ransomware attack. A firm in that position is a business associate, so the client's patient data in your workpapers carries HIPAA duties of its own, AI or no AI.