An AI tool can explain a variance, draft the email to the client, write the spreadsheet formula and spot a duplicated payment. It does not need to know whose books they are. This is how to prepare client financial files so the numbers go in and the identities stay out.
What a bank export and a set of statements reveal
A file can identify a client in places you do not look at while working. In a typical export or workbook:
- The header. Account holder name, account number or IBAN, branch, statement address.
- The transaction lines. Counterparty names, and free-text references such as "rent March, J. Alvarez". Some counterparties are individuals: landlords, contractors, relatives.
- Payroll and expense lines. Employee names, sometimes with tax or insurance numbers.
- The workbook itself. Sheet names, hidden sheets, cell comments, headers and footers, and the author in the file properties.
- The statements. Company name, registered address, signatory names in the notes, and the auditor.
Amounts and dates are usually what the analysis needs. Names and numbers that identify a person or an account usually are not.
What AI can do with it
These tasks work well on a prepared file:
- Explaining why a line moved between periods, once you give the figures.
- Grouping transactions into categories and listing the ones it cannot place.
- Finding repeated amounts, round-sum payments and possible duplicates.
- Writing and fixing spreadsheet formulas.
- Summarizing a lease, loan agreement or engagement letter that came with the books.
- Drafting a plain-language note to the client.
Check its arithmetic. These tools make calculation errors, and a subtotal that looks right can be wrong. Recompute anything that goes into a deliverable.
What to strip before you send
- The client. Entity name, trading names, owners and officers.
- Account identifiers. Account numbers, IBANs, card numbers, tax and company registration numbers.
- Counterparties. Customers, suppliers, landlords, lenders. A large supplier is not a privacy problem, but an individual often is, and a supplier name can still reveal the client's business.
- People. Employees, directors, signatories, and names inside payment references.
- Addresses, phone numbers and email addresses, including those in statement headers and letterheads.
- File and sheet names. "Lopez Bakery 2025 final.xlsx" tells the AI everything.
The full checklist covers the places people forget, such as hidden sheets and comments.
Keep the replacements consistent
Bank data is repetitive on purpose. The same landlord appears every month. If that landlord is Company_3 in January and Company_7 in March, the AI cannot see a recurring payment, and any question about trends or duplicates gets a worse answer.
Use one placeholder per party across the whole file, and across all files for the same client. If you work from twelve monthly statements, they are one set. The article on working with a whole case covers that setup.
Leave the amounts and dates alone unless a figure is itself identifying. A unique, well-known amount paid to a named person can point to a specific transaction.
A short example
A line from a bank export:
2026-03-04 SEPA transfer J. ALVAREZ rent March unit 4 -1,850.00 Account 4471 0098 2231
The version you send:
2026-03-04 SEPA transfer Person_3 rent March unit 4 -1,850.00 Account_2
The AI can still tell you that this is a monthly rent payment, that it has moved from the 1st to the 4th, and that it is missing for April. It cannot tell you whose rent it is. The reference "unit 4" is borderline in a small building, so read lines like that before you send them.
Send a sample when the question is about structure
If the question is "how do I categorize these lines" or "what formula sums by month", you do not need the full ledger. Paste ten rows with placeholders and ask for the method. Apply it to the real file in your own spreadsheet. The AI never sees the rest.
Bank PDFs and scanned statements
Many clients send statements as PDFs, and some as scans or photos from a phone. A scanned page is a picture, and the account holder's name and number are in it. Do not upload the scan to an AI tool as it is. Turn it into text first, replace the identifiers, and send that.
Mistakes that expose the client anyway
- Uploading the workbook instead of pasting the data. Hidden sheets, comments and the author field travel with the file.
- Cleaning the cells but not the memo column. Free-text references are where first names, flat numbers and invoice nicknames live.
- Forgetting the PDF behind the spreadsheet. A scanned bank statement attached to the work is a picture, and the account holder's name is in it. See personal data hiding in scans and screenshots.
- Mixing clients in one chat. Keep one client per conversation so placeholders and answers never cross over.
- Pasting the key into the chat to "help" the AI. Then nothing was replaced.
Put the names back afterwards
When the AI says "Company_3 shows three payments of the same amount in one week", you need to know who Company_3 is. Restore the real names in its answer on your own computer, read it, and only then use it in a working paper or an email. The method is described in the round-trip workflow.
Frequently asked questions
Do I have to remove the amounts?
Usually not. Amounts are what the analysis runs on. Remove them only if a figure alone would identify a person or a transaction.
Does my engagement letter or professional body say anything about AI?
Possibly. Check your engagement terms, your professional body's guidance and the confidentiality rules that apply to your work before you decide what may be sent.
Which file types work with ClientSafe?
PDF (including scans), DOCX, XLSX, PPTX, CSV, HTML, TXT, EML, EPUB, FB2 and MOBI. Hidden sheets in XLSX files are read too.
ClientSafe replaces client names, companies, account numbers and addresses with consistent placeholders in a safe copy of the file, on your PC. You review what it found, untick false matches and mark what it missed. Your original file stays unchanged.
General information, not professional advice. Check the rules that apply to you.