Do foreign-born children inherit Thai nationality?

Yes by jus sanguinis if either parent is Thai.

Must a Thai with a US passport declare it?

No formal declaration; but you must enter/exit Thailand on the Thai passport.

Dual Citizenship Consultation

ปรึกษาเรื่องสองสัญชาติ (Dual Citizenship) · § Status

Quick Answer

Analysis of both nationality laws (Thai Section 22 + home country), plus tax residency, estate, and conscription implications.

Timeline: 1–3 consultation sessions (2–6 weeks).

Official fee: No official fee (beyond registering an overseas-born Thai child).

Legal Basis

Nationality Act B.E. 2508 · Thai law permits dual nationality for citizens by birth; naturalized citizens must renounce prior nationality (Section 13).

Who Needs This

Thai-foreign children, Thais born abroad, Thai nationals who naturalized overseas, prospective naturalized Thais.

Required Documents

Birth certificates (Thai + foreign)
Both passports
House registration
Parents' nationality proof
Residency / tax records

Common Pitfalls

Section 22 can strip Thai nationality if you don't affirm at majority
Male dual nationals still owe Thai conscription
Some countries (China, India) forbid dual nationality outright

Typical Use-cases

Half-Thai children (renewing Thai passport)
Thais gaining US citizenship
Registering foreign-born Thai children
Cross-border tax planning

FAQ

Do foreign-born children inherit Thai nationality?: Yes by jus sanguinis if either parent is Thai.
Must a Thai with a US passport declare it?: No formal declaration; but you must enter/exit Thailand on the Thai passport.