What NAATI accreditation actually guarantees, and what it does not
NAATI is the Australian body that credentials translators and interpreters. A certified translation identifies the practitioner, records their credential and carries their declaration that the English corresponds to the Thai source. That is the assurance the receiving officer wants: a named professional who can be checked and who has accepted responsibility. Nothing about accreditation changes the content of your document, so a Thai record that is internally inconsistent will simply produce an English version with the same inconsistency, now visible to the assessor.
This is why we read the Thai original before translating rather than after. Where a household registration spells a name differently from a passport, where a marriage record was amended by hand, or where a district office used an obsolete form, we tell you before the file is submitted and advise whether the underlying Thai record should be corrected first. Correcting a district record takes days; answering a request for further information from an overseas department takes months.
Accreditation also does not replace document legalisation. Some receiving bodies want the translation certified and nothing more; others want proof that the Thai document itself is genuine, which runs through the issuing authority, the Department of Consular Affairs and sometimes the destination embassy. We ask which of those two things your recipient wants, because ordering the wrong one wastes both money and weeks.