At some point this year someone will ask you for a copy of your passport. A letting agent wants it before a viewing, a recruitment agency wants it alongside your CV, a new employer asks for it before your first day, or a holiday let host wants proof of who is turning up. You take a photo of the open page, attach it to an email and press send without a second thought.
That photo then lives a long and untidy life. It sits in an inbox, gets forwarded to a colleague, lands in a shared folder and is downloaded to a laptop that may or may not be encrypted. You have no say in any of it, and there is nothing on the image to show where it was meant to go. If it ever turns up somewhere else, nobody can tell it was never yours to use.
A watermark fixes that last part. It is a line of text written across the copy that says who it is for, what it is for and when you sent it. It takes about a minute, costs nothing and makes a copy much harder to pass off for some other purpose. Here is how to do it properly in the UK, what to write, and where people usually go wrong.
Why an emailed passport copy needs a watermark
The Information Commissioner’s Office lists a lost or stolen passport or driving licence among the first signs that you may be a victim of identity theft, and advises keeping documents that carry personal information somewhere safe. A copy sitting in a stranger’s inbox has not been lost or stolen, but it is out of your hands, and nobody is obliged to tell you if that inbox is ever compromised.
A watermark does not stop anyone reading the copy. What it does is tie the copy to one purpose. A passport image marked as being for a particular letting agent and a particular month looks wrong when it is attached to a loan application or a new phone contract. That mismatch gives whoever is checking a reason to stop and look, and it gives you something to point to.
There is also a quieter benefit. Writing the line forces you to think about who is asking and why. If you cannot finish the sentence “this copy is for”, it may be worth asking the person what they actually need before you send anything. Under the UK GDPR’s data minimisation principle, as the ICO explains it, organisations should hold only personal data that is adequate, relevant and limited to what is necessary for their purpose, so it is fair to ask them what theirs is.
What the letting agent or employer actually checks
Two of the usual reasons for being asked for a passport in England are the right to rent and right to work checks, and in both the Home Office makes clear that an emailed copy does not count. The landlord’s guide says landlords and agents must be in physical possession of the original document, check it in the presence of the holder, in person or by live video call, and must not rely on a faxed, scanned or copied version.
Employers follow a similar pattern. GOV.UK says that for British and Irish citizens, who cannot get an online share code, the employer must check the original document, such as a passport or passport card, or use an identity service provider that offers document validation technology. The employer then makes its own copy that cannot be changed and keeps it during your employment and for two years afterwards.
Landlords keep their copy for the length of the tenancy and at least a year after it ends. In other words, the copy that counts is made from the original, by the landlord or employer, at the check itself. The scan you email in advance is a convenience for the office, and it is exactly the kind of copy that travels, gets forwarded and gains most from a watermark.
What to write in a passport watermark
A good watermark answers three questions: who the copy is for, what it is for and the month you sent it. Something like “Copy for the letting agent only, Mill Lane flat, October 2026” does all three. So does “Copy for the agency only, warehouse role, October 2026” or “Copy for onboarding only, October 2026”. Swap in the real recipient, purpose and date each time.
What does not work is a single word. “Copy” or your initials tell a later reader nothing about where the image was meant to go, and “Not valid” invites the question of what it is valid for. Keep the line short as well. A sentence of five to ten words stays legible across the page at an angle, while a paragraph turns into grey texture that nobody will bother to read.
Put the line where it cannot be cropped out. That means across the photo and the printed details, not in an empty margin. Repeating it diagonally across the whole page is the hardest layout to remove and the better choice for anyone you have not met. A single line through the middle of the data page is easier to read and suits an office that has already seen you in person.
Making the watermark stick
The classic mistake is adding the watermark as a text box over the image in a PDF editor or a slide. It looks fine on screen, and the recipient can delete it with one click. The text has to become part of the image itself, so that getting rid of it means editing the photo. Exporting the result as a flat JPG or PNG is the simplest way to make sure.
Check what else the file carries. A photo taken on a phone may include the location where it was taken, and a scan of the full book can include more than the data page. On the current blue passports, page 3, the Official Observations page, carries your handwritten signature, which the person asking rarely needs. Photograph the data page on its own, crop tight to its edges and look at the image before it goes.
None of this needs special software, though a tool built for the job saves fiddling with layers. If you would rather not do it by hand, this walkthrough on how to watermark a passport copy goes through the UK passport field by field, suggests wording for each kind of request and includes a tool, with no sign-up, that writes the line across a photo or scan and exports it as a PNG, JPG or PDF.
Passport scans, text extraction and AI tools
Passport copies also end up in online converters and AI chatbots, usually because someone wants the details typed into a form for them. It is worth knowing what those tools see. The two lines of letters, numbers and chevrons at the foot of the data page form the machine readable zone, set by ICAO Doc 9303 as two lines of 44 characters, repeating your name, passport number, nationality, date of birth and expiry date.
That zone exists to be read by machines, and text recognition software has no trouble with it. Covering the printed details but leaving those two lines visible gives most of the information away. If a tool only needs your name, crop or cover everything else, the bottom lines included, before you upload. The same goes for an employer pasting a new starter’s details into an AI to fill in payroll forms.
Firms that process passports by the dozen can take the text side off their staff’s plate. Nonimo, a desktop app for Mac and Windows, picks out names, passport numbers, bank details and other personal data and puts placeholders in their place on the computer, before anything is sent to ChatGPT, Copilot or Gemini. The paperwork still gets drafted, with the real details kept back.