What makes a betrothal valid?

A betrothal becomes legally effective only when the man gives or transfers the khongman (ของหมั้น) to the woman. Once given, the khongman immediately becomes the woman’s property. Betrothal gives no right to compel marriage and any “penalty” clause for not marrying is void. (senate.go.th)

Khongman (ของหมั้น), can it be taken back?

General rule: If either party breaches the betrothal, the non-breaching party may claim compensation. If the woman breaches, she must return the khongman; if the man breaches, the woman keeps it. (senate.go.th)

Death before marriage: If either fiancé(e) dies before marriage, no compensation can be claimed, and neither khongman nor sinsod need be returned.iad.dopa.go.th

Limitation periods & restitution rule: Claims connected to betrothal (including return of khongman/sinsod) follow short limitation periods (generally six months, depending on the claim). Returns are governed by the Civil Code’s undue-enrichment provisions (Sections 412–418) mutatis mutandis. doi.nrct.go.th

Who owns the khongman after marriage?

Because the khongman became the woman’s property before marriage, it remains her personal property (สินส่วนตัว) during marriage under Section 1471(1) (property owned before marriage). Government guidance reiterates this personal-property rule. gcc.go.th +1

Sinsod (สินสอด), what is it and can it be reclaimed?

Sinsod is a separate gift: property the man gives to the woman’s parents/guardian as consideration for her agreement to marry. If no marriage occurs due mainly to a cause on the woman’s side (making marriage unsuitable or impossible for the man), the man may claim the sinsod back. gcc.go.th

Is giving sinsod “common” or required?

Thai law recognizes sinsod and explains its function, but does not mandate it for the betrothal to be valid (validity turns on the khongman). Official public-information pages from Thai agencies describe sinsod as customary consideration to the parents, not a legal prerequisite to betrothal. gcc.go.th

At-a-glance statutory points (all from the Civil and Commercial Code, official summaries/quotations):

• section 1437: Betrothal is complete when khongman is delivered; khongman becomes the woman’s property; sinsod defined; return rules via undue-enrichment. senate.go.th +1
• section 1438: No action to force marriage; penalty clauses are void. senate.go.th
• section 1439–1440: Breach → compensation; woman’s breach → return khongman. senate.go.th
• section 1441: Death before marriage → no compensation; khongman/sinsod not returnable. iad.dopa.go.th
• section 1447/1–1447/2: Six-month limitation periods for compensation and return of khongman claims. doi.nrct.go.th
• section 1471(1): Property owned before marriage is personal property (covers khongman once the couple later marries). bora.dopa.go.th

Sources (official Thai)

• Thai Senate newsletter summarizing sections 1437–1440 with verbatim text and case-law notes — senate.go.th
• Government public-information page explaining khongman and sinsod and when sinsod can be reclaimed — gcc.go.th
• Department of Provincial Administration (DOPA) note reflecting section 1441 (no return of khongman/sinsod if a fiancé(e) dies) — iad.dopa.go.th
• National Research Council of Thailand (NRCT) repository citing undue-enrichment cross-reference and six-month limitation rules (§§1447/1–1447/2) — doi.nrct.go.th
• Bureau of Registration Administration (DOPA/BORA) explainer quoting section 1471 (personal vs. marital property), bora.dopa.go.th