TDAC rejects my name, passport or phone: the exact rules
Checked 5 November 2026 by Darius Cheung. Independent guide, not a government website.
TDAC fields accept narrow sets of characters. First and middle names take English letters and spaces only, and family names add one exception: a lone dash. So an apostrophe or hyphen fails. Passport numbers take letters and digits with no spaces, and phone numbers take digits only. Type names the way the machine-readable lines at the bottom of your passport print them, without the punctuation.
What each field accepts
These rules come from the validation code in the form itself. If a field is marked in red, compare what you typed with this table.
| Field | Accepts | Max | Fails on |
|---|---|---|---|
| Family name | English letters and spaces, or a single - | 60 | O'BRIEN, SMITH-JONES, MÃœLLER |
| First name | English letters and spaces | 60 | JEAN-LUC, JOSÉ, a lone - |
| Middle name | English letters and spaces (optional) | 60 | J. |
| Passport number | Letters and digits | 20 | Spaces or dashes |
| Phone number | Digits only (the code is a separate box) | 25 | +65 9123, brackets, dashes |
| Visa number | Letters, digits, spaces, /, - (optional) | 20 | A first character of = + @ - |
| Occupation | English letters, symbols, spaces | 100 | Digits, non-English script, or a first character of = + @ - |
| City of residence | Letters and common punctuation | 100 | Emoji, or a first character of = + @ - |
| Flight or vehicle number | English letters, digits, symbols, spaces | 20 | Non-English script, or a first character of = + @ - |
| One normal address | 50 | Two addresses, or one over 50 characters |
If your name has an apostrophe, hyphen or accent
Look at the two machine-readable lines at the bottom of your passport's photo page. International passport standards remove apostrophes, replace hyphens with a filler, and convert accents into plain letters, so those lines already show a form of your name the system can handle. For example:
O'BRIENprints asOBRIEN, so typeOBRIEN.SMITH-JONESprints asSMITH<JONES, so typeSMITH JONES.- An accented
MÃœLLERmay print asMUELLERorMULLER. Use what your passport's lines show.
This is our reading of the standard and the form's rules. It isn't official advice from Thai immigration, who have the last word at the border.
If you have no family name
Some passports show only one name. The family name pattern allows exactly one dash and nothing else, which suggests - is the intended entry. The form requires this box, so an empty one fails. First name has no such exception.
Things that catch people out
- Letter O and number 0. The most common passport typo. The form can't spot it, because both are valid characters.
- Pasted spaces. Copying from a booking email can bring a space with it, which fails on the passport number.
- You won't see the error until you leave the field. The form checks a value when you click away from it, so it can look fine while you're typing.
- You can't update a name later. The site says full name can't be updated after submission, so a typo there means a new submission.
Uploads have rules too: a passport image must be JPG, JPEG, PNG or BMP up to 5MB, and a vaccination certificate must be JPG, JPEG, PNG or PDF up to 5MB with a file name under 250 characters.
Questions people ask
Does the TDAC have to match my passport exactly?
The form says full name in passport. Since it can't accept punctuation, use the plain-letter form shown in your passport's machine-readable lines.
Do I type my phone's country code twice?
No. The code goes in its own box and the number field takes digits only. Leave out the plus sign.
Can I write my hotel in Thai?
No. The address field rejects Thai script. See the accommodation guide for what to type.
Once your name and passport are accepted, you shouldn't have to work it out again. ArrivalFiller replays what you typed the first time, ready to check.
Add ArrivalFiller to Chrome, freeWhere this comes from
Rules change, so check the official site before you travel. Where we quote a form's message, we copied it from the form's own public code. Some messages may rarely appear, and we don't run test submissions on government forms.
- TDAC site's public code and English text (official site, version 2026.10.00-0547, read by us on 3 Nov 2026)
- Royal Thai Embassy, Buenos Aires: How to submit the TDAC (official, updated 26 Feb 2026)