Which side of your ID do you need to copy — front, back, or both?

“Front and back, please.” It sounds like a formality, and most people photograph both without stopping. It is worth stopping, because the two sides are not equivalent — and on a card, the one people treat as the boring half is the one that gives the most away.

The card: the back is the sensitive side

Every card-sized identity document follows the same international layout, set out in ICAO Doc 9303 Part 5. It divides the card into zones: the front holds the visual inspection zone — portrait, name, document number — and the machine-readable zone gets its own zone on the reverse. The standard leaves no room for interpretation: “The MRZ is located on the back of the TD1.”

TD1 is simply the standard’s name for a credit-card-sized document. Spain’s DNI, for instance, is specified by its own issuing authority as ID-1 format, 85.6 × 53.98 mm — the same footprint — so the layout applies.

That strip is three lines of 30 characters that restate your document number, date of birth, sex and expiry date in a form designed to be lifted by a scanner in one pass. It is the single most concentrated block of identity data on the document.

So the common instinct — cover the number on the front, send the back untouched because “it’s just the address” — gets it exactly backwards. The back is where the number lives again, in machine-readable form, next to everything else.

The passport: one page, and only one

A passport is the easier case. All of the identity data sits on a single page: the photo page carries your name, document number, nationality, date of birth, expiry date and the two-line machine-readable zone at the bottom, laid out as Part 4 of the same standard specifies.

Every other page is visas and entry stamps. That is not identity data — it is a travel history, and it answers a question nobody asked. A hotel checking you in does not need to know which countries you entered last year.

If someone asks for “a copy of your passport” without qualification, they mean the photo page. Send that, redacted, and let them come back if they genuinely need more.

How to decide, in one question

Ask: what does this person have to verify?

• That the face matches the booking — the front of a card, or the passport photo page, with the number and machine-readable zone covered.
• That you live where you say — whichever side carries the address, with everything else covered. Often a utility bill is the better document.
• That the document has not expired — the expiry date, which you can leave visible while covering the rest.

Then cover everything that does not serve that answer. Our scenario guides work through the common ones: a landlord, a hotel, an Airbnb host, an employer.

Some requests genuinely need an unredacted document — a bank opening an account is the clearest example, and trying to redact your way through that will just fail the check.

Whatever you send, mark it as a copy

A copy that is obviously a copy is far less useful to anyone who might reuse it. Write across it who it is for and why, tiled so it cannot be cropped away — the full method is in how to watermark a copy of your ID.

In Germany this is not merely good practice. § 20 Abs. 2 PAuswG requires that a copy of the Personalausweis be eindeutig und dauerhaft als Kopie erkennbar — clearly and permanently recognisable as a copy — and that the recipient may not pass it on.

Anonymize my ID handles both sides of a card in one pass, on-device, and puts the watermark on for you.

Frequently asked questions