Section 42: Calculation of detention period
Statutory text (Thai original)
ในการคำนวณระยะเวลากักกัน ให้นับวันที่ศาลพิพากษาเป็นวันเริ่มกักกัน แต่ถ้ายังมีโทษจำคุกหรือกักขังที่ผู้ต้องกักกันนั้นจะต้องรับอยู่ก็ให้จำคุกหรือกักขังเสียก่อน และให้นับวันถัดจากวันที่พ้นโทษจำคุกหรือพ้นจากกักขังเป็นวันเริ่มกักกัน ระยะเวลากักกัน และการปล่อยตัวผู้ถูกกักกัน ให้นำบทบัญญัติมาตรา ๒๑ มาใช้บังคับโดยอนุโลม
English translation
In calculating the period of detention, it shall be counted from the date of the court's judgment. If there is a term of imprisonment to be served before detention, the imprisonment shall be served first, and detention shall begin from the day following the day of release from imprisonment.
The provisions of Section 21 shall apply mutatis mutandis.
This English translation is provided for reference only and has not yet been firm-verified. Always rely on the Thai original.
Firm annotation
Section 42 governs the timing of a detention order made under Section 41. As a rule the period runs from the date of judgment, but where the offender also has a prison term to serve, imprisonment comes first and detention starts the day after release, so the two do not overlap. The section borrows the time-counting method of Section 21 (the rule for computing terms of confinement) by analogy. It completes the habitual-offender scheme of Sections 40 and 41 by fixing when the three-to-ten-year detention period begins and how it is measured.
Why this matters in practice
For anyone facing both imprisonment and detention, the practical point is sequence: you serve the prison term first, and the three-to-ten-year detention only begins the day after you are released, so the total time in custody can be substantial. Because detention runs consecutively, not concurrently, with imprisonment, the real exposure of a habitual-offender case is the prison term plus the detention period. Section 21's counting rules apply, so the start and end dates should be checked precisely.
Cited in 5 Supreme Court decisions (1967 to 2017)
Selected citing decisions
- Decision 1341/2521 (1978)
- Decision 5059/2560 (2017)
- Decision 1635/2537 (1994)
- Decision 196/2510 (1967)
- Decision 7330/2540 (1997)
This list is selected automatically, weighted towards judgments that turn on this section rather than ones that merely recite it when passing sentence. It has not yet been reviewed by the firm.
Counted across the firm's corpus of 83,652 Supreme Court decisions, 1921 to 2026. The count is complete; the stated year range trims rare outliers so it describes where the citations actually sit. These figures are computed by us and are not official court statistics. How we count these, and what we measured
Frequently asked questions
When does the detention period start in Thailand?
Under Section 42 it runs from the date of judgment, but if the offender must serve imprisonment first, detention begins the day after release from prison.
Does detention run at the same time as a prison sentence?
No. Imprisonment is served first and detention begins the day after release, so they run consecutively, not concurrently.
Cite this section
-
Plain citation
Penal Code, s. 42 (Thailand) -
Academic citation
Penal Code (Thailand), s. 42. ThaiLawOnline, https://www.thailawonline.com/thai-penal-code/section-42/ (accessed 17 August 2026). -
Thai citation
ป.อ. มาตรา 42 -
Permalink
https://www.thailawonline.com/thai-penal-code/section-42/ -
Embed on your site
<blockquote cite="https://www.thailawonline.com/thai-penal-code/section-42/"><p>In calculating the period of detention, it shall be counted from the date of the court's judgment. If there is a term of imprisonment to be served before detention, the imprisonment shall be served first, and detention shall begin from the day following the day…</p><footer>Penal Code, s. 42 (Thailand) — <a href="https://www.thailawonline.com/thai-penal-code/section-42/">ThaiLawOnline</a></footer></blockquote>
The Thai text is authoritative. The English is an unofficial translation by ThaiLawOnline, free to reuse with attribution.