This is the classic. After years of reading passports at GetETA we still get caught by it: a passport number with a character that could be the letter O or the digit 0. Many European passports mix letters and digits, the fonts are small, the letters are not much wider than the digits — and most people do not even know there is a question. They type what they think they see, pay, and get the worst possible result: an eTA that looks approved and matches no passport.
At check-in the airline scans the passport chip. The chip says 0. The eTA says O. Nothing is found. No amount of “but I have the approval email” helps.
The usual suspects
| Looks like | Could be |
|---|---|
| O / 0 | letter O or digit zero — the big one |
| I / 1 / l | capital I, digit one, lowercase L |
| S / 5 | letter S or digit five |
| B / 8 | letter B or digit eight |
| Z / 2 | letter Z or digit two |
| G / 6 | letter G or digit six |
| D / 0 | letter D or digit zero in some fonts |
How to tell for certain: the two lines at the bottom
Every modern passport has two lines of capital letters, digits and < symbols at the bottom of the photo page — the machine-readable zone. This is what the airline and the border actually read. Your passport number is there, in the second line, at the very start — and it is printed in a font designed so that letters and digits cannot be confused: the zero is narrower than the O, the one has no serif, and many countries simply never use O or I in passport numbers at all.
So: do not read the number from the big printed field. Read it from the second line at the bottom. If you have a clear photo, zoom in on that line. Compare the doubtful character with a known letter and a known digit elsewhere in the same line — the < fillers and the country code (letters) and the date of birth (digits) are right there for comparison.
There is an extra trick for the truly stubborn cases. Right after the passport number in that line there is one check digit. It is calculated from the number itself, and it gives a different result for O (counted as 24) than for 0 (counted as 0). Online MRZ check-digit calculators exist; paste the number with O, then with 0, and only one will produce the check digit printed in your passport. That is a definitive answer, not a guess.
Two country hints that help
- Many European countries avoid ambiguous characters entirely. If your passport is, say, German, the number simply will not contain an O or an I — so if you “see” one, it is a 0 or a 1.
- Some countries use letters only, or digits only. If every other character is a digit, the doubtful one almost certainly is too.
Neither hint replaces reading the bottom line, but they tell you which way to lean.
If you really cannot tell
This is what we do when even the bottom line does not settle it: photograph the passport number — just that strip, sharp and large — and send it to someone who reads passports for a living. We do this ourselves; for our clients we handle it as part of the application. If you are applying on your own and are stuck, write to the processing office through their web form, attach the photo of the number, and ask. They can read the characters correctly — and, if an application already exists, they can see which one it was filed under. Sometimes this is the only thing that resolves it.
If you have already applied with the wrong character
- Check which version the eTA was filed under. Run a status check with the number as it is on the passport’s bottom line. Found → you are fine, it was approved under the correct number. Not found → try the other character. If it only exists under the wrong one, it will not work at the airport.
- Do not fly on it. It looks approved; it is not attached to your passport.
- Apply again with the correct character, reading from the bottom line. Be aware: a second application on a passport that already has one often goes to a manual review and can take longer than minutes — why that matters — so do it today, not the day before the flight.
Avoiding it altogether
- Read the number from the bottom machine-readable line, never from the big field.
- Read it aloud, character by character, to someone looking at the same image.
- If you are filling in forms for several family members or for relatives abroad, work from a scan, never from a number read over the phone — “oh” and “zero” sound different, but “O” and “0” on a WhatsApp message do not.
- Or send us the passport photo and let us read it. This exact character is one of the main things our review catches before anything is submitted.
Official information: eTA facts