Do I need a lawyer to register my marriage in Thailand?

No — Thai marriage registration is an administrative act handled by any District Office (ที่ว่าการอำเภอ / Amphur), and it is one of the simpler procedures available to foreigners. A lawyer is not legally required, but there are three points at which professional help is worth its cost.

Stage 1 — Affirmation of freedom to marry. Your home embassy in Bangkok must issue an affidavit confirming you are single and free to marry under your home law. This is typically a same-day appointment but fees vary widely (US$50–US$300+). Thai authorities then require the affidavit to be translated into Thai and legalised by the Ministry of Foreign Affairs (กระทรวงการต่างประเทศ) at Chaeng Watthana. Lawyers and translation agencies can run this as a service for THB 2,000–5,000.

Stage 2 — Registration at the Amphur. Both parties attend in person with passports, the legalised affidavit, the Thai translation, and two witnesses (often friends, or staff at the office). The registrar will issue the Khor Ror 2 (ใบสำคัญการสมรส) marriage certificate on the spot. No lawyer required.

Stage 3 — Prenuptial agreement (สัญญาก่อนสมรส). This is where you should engage a Thai lawyer. Under Section 1466 of the Civil and Commercial Code, a prenuptial agreement is only valid if it is registered at the Amphur on the same day as the marriage itself and recorded on the marriage register. It cannot be added later. If you have any pre-marital property, business interests, or expect inheritances, draft it bilingually with a lawyer at least 2–3 weeks before the wedding date.

Bottom line: lawyer optional for the marriage itself, strongly recommended for a prenup.