How to Redact Bank Account Numbers in a PDF
To redact bank account numbers in a PDF, you have to remove the digits from the file itself, not just cover them, because a black box or highlight leaves the number selectable and searchable underneath. In Gold PDF, search for each number in short pieces, press R to mark every occurrence, and save: the pages with redactions are rebuilt so the numbers no longer exist in the document.
Quick steps
- Decide what must go: the full account number, or everything except the last four digits.
- Open the PDF in Gold PDF and use Save as to keep a private, unredacted original.
- If the document is a scan or a photo, press Ctrl+Shift+O to run OCR.
- Press Ctrl+F and search for the last four digits, the first four digits and any middle group of each number. Note every page with a hit.
- Read the header, footer, transaction lines and any cheque images by eye.
- Press R and drag a box over each number, slightly larger than the digits.
- Press Ctrl+S, close the file, reopen it and search again. Nothing should be found.
- Rename the file if its name contains any part of the number.
Why bank numbers leak from PDFs
Bank details travel in many documents: statements sent to a landlord or a mortgage broker, invoices with payment details, payroll forms, court and divorce filings, insurance claims and tax paperwork. In most of these cases the reader needs some of the document but not the full account number.
The leaks come from a few predictable places:
- Covering instead of removing. A black rectangle drawn with a shape tool, a black highlight, or Whiteout. The number disappears on screen but is still in the file. Copying the area and pasting it into Notepad brings it back. The reasons are explained in does drawing a black box redact a PDF.
- Repeated numbers. A statement usually prints the account number in the header of every page, not just the first one.
- Numbers in transaction lines. Transfers between your own accounts, standing orders and direct debits often show another full account number in the description.
- Formatting. The same number written with spaces on page one and without spaces in a footer. A single search misses one of them.
- Images. Scanned cheques, a photographed bank letter or a screenshot pasted into an invoice. Search does not see digits inside an image until you run OCR.
Which bank numbers to look for
"Account number" can mean several different numbers, and a single document can contain more than one of them. The table below lists the usual suspects and whether they normally need redacting. Requirements vary, so treat it as a checklist, not a rule.
| Number | Where it appears | Usually redact? |
|---|---|---|
| Account number | Statement header, payment details, transfer lines | Yes, fully or all but the last four digits |
| IBAN | Invoices, international payment details | Yes, it contains the account number |
| Routing number, sort code or BIC | Next to the account number | Often left in, since it identifies the bank, not you; remove it if asked |
| Card number | Card statements, receipts | Yes, all but the last four digits at most |
| Card expiry date and security code | Rarely printed; sometimes in photographed cards | Always |
| Customer or reference number | Statement header, letters | Often, since it can be used to identify you at the bank |
| Online banking username | Letters and welcome packs | Always |
A routing number or sort code on its own is shared by everyone at that branch or bank, so many people leave it visible. The account number next to it is the part that belongs to you.
How to find every account number in the file
Search works well for numbers, but only if you search in small pieces. For an account number like 0123 4567 8901, search separately for:
- 8901, the last four digits. This catches the number whether it is written with spaces, dashes or neither.
- 0123, the first four digits.
- 4567, the middle group.
- The full number written both ways: 012345678901 and 0123 4567 8901.
Step through every result with Ctrl+F and write down the page numbers. Expect some false matches, such as an amount of 89.01 or a date: skip those, but look at each one.
Then do a visual pass at 150% to 200% zoom. Check the header and footer of every page, every transfer line, the payment slip at the bottom of an invoice, and any image of a cheque or card. Search finds the numbers you knew about; reading finds the ones you did not.
On scanned statements, OCR can misread digits, for example 1 as l or 0 as O. After running OCR with Ctrl+Shift+O, search for shorter pieces, such as three digits, and rely more on the visual pass. The full routine for scans is in how to redact a scanned PDF document.
How to redact the numbers
Press R to open the Redact tool and drag a box over each number. Make the box a little wider and taller than the digits so no edge of a character remains. If the number sits in a narrow table cell, covering the whole cell is often cleaner.
When you press Ctrl+S, Gold PDF rebuilds each page that contains a redaction. The page is rendered as a high-resolution image with the black bars burned in, and the remaining words are added back as an invisible text layer so you can still search and copy the rest of the statement. The redacted digits are not in that layer. Pages without redactions are left as they were.
Keeping the last four digits
If the reader needs to know which account is meant, redact only the leading digits. Drag the box from the first digit up to, but not including, the last four. Zoom in before you drag, since a box that clips half of the fifth-from-last digit can leave it readable. The result reads like a masked number: a black bar followed by 8901.
If you would rather show a typed mask, such as XXXX XXXX 8901, redact the full number with R, then press E, click the line and type the masked version. Editing text with E also rebuilds the page on save, so the original digits do not survive under the new text.
Check the file before you send it
A bank number sent by email cannot be pulled back, so test the saved copy every time:
- Reopen the redacted file from disk.
- Search for each piece of each number again. There should be no results, apart from any last four digits you chose to keep.
- Copy across each black bar and paste into Notepad. Nothing from under the bar should appear.
- Zoom in on each bar to make sure no part of a digit is visible.
- Check properties for the title, subject and keywords. Steps are in how to remove metadata from a PDF before sharing.
- Check the file name.
A longer checklist is in how to check if a PDF redaction is secure.
Should you redact at all, or send less?
Sometimes the safest redaction is not sending the page. If a landlord needs proof of income, one page of the statement showing the salary payment may be enough, rather than three months of transactions. Ask what the reader actually needs, remove the pages they do not, and redact the rest. Fewer pages also means fewer places for a number to slip through.
If the document has to travel by email and the reader needs the full details, a password is another layer: see how to password protect a PDF for free. A password protects the file in transit; it does not replace redaction when the reader should not see the number at all.
What Gold PDF does and does not do
Gold PDF is a free, offline PDF editor for Windows. Its Redact tool (R) removes the content under each box when you save, by rebuilding only the pages that contain redactions, and it can run OCR on scanned statements (Ctrl+Shift+O, English and Hebrew bundled) so you can search them. The file stays on your computer the whole time, which matters for a document full of bank details. It does not find account numbers for you: searching for every number and reading each page is your job. It does not connect to your bank or check whether a number is valid. It runs on Windows only, not on Mac, Linux or phones. For an overview of the tool, see Redact a PDF.
Frequently asked questions
Is it safe to cover a bank account number with a black box?
No. A drawn box, a black highlight or Whiteout only hides the number on screen. Anyone can still select, copy or search the digits underneath. The number has to be removed from the file, which is what a real redaction does on save.
Should I redact the whole account number or leave the last four digits?
Many people leave the last four digits so the reader can tell which account is meant, and that is common on statements. Follow whatever the person or organisation asking for the document requires. If nobody needs the account identified, remove the whole number.
How do I find account numbers that are split by spaces or dashes?
Search for short pieces instead of the full number: the last four digits, the first four digits, or a middle group. A number written as 1234 5678 or 1234-5678 will not match a search for 12345678, but each group on its own will.
Can I redact account numbers in a scanned bank statement?
Yes. Run OCR first (Ctrl+Shift+O in Gold PDF) so the digits can be searched, then redact each one. The redacted page is rebuilt as an image with the bar burned in, so the number is gone from the picture and the text layer.
Does the account number also need to be removed from the file name?
Yes, if it is there. Banks often name downloaded statements with part of the account number. Rename the redacted copy before you send it.
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