In this article, we explain how to count time under Thai law in simple, practical language. In everyday life, we talk about time casually, but in the legal system one miscalculated day can mean winning or losing a case, missing a court deadline, or even staying in prison longer than necessary.
In everyday life, we talk about time in a very casual way.
“See you in three days.”
“Pay within one month.”
“Turn 60 next year.”
But in the legal world, one single miscalculated day can decide whether:
- a lawsuit is filed in time or is already time-barred,
- a party meets or misses a court deadline, or
- a defendant spends an extra full day in prison.
Thai law therefore has specific rules for counting time, depending on the legal purpose. In this article, we explain three key systems:
- General time periods (deadlines, contracts, limitation) – usually use the rule “exclude the first day”
- A person’s age – uses the rule “start counting from the birthday itself”
- Imprisonment or detention – uses the rule “any fraction of a day counts as a full day”
All explanations below are based on the Thai Civil and Commercial Code (CCC) and the Thai Criminal Code, and are written in a foreigner-friendly way for information only.
1. How to Count Time under Thai Law for General Civil Deadlines
When Thai law sets deadlines for civil matters – such as contractual performance, limitation periods, or time limits to file pleadings, it does not always count days the way we do in daily life. To understand how to count time under Thai law for civil and commercial matters, we need to start with the basic rule that the first day is usually not counted.
1.1 Time periods expressed in “days”: exclude the first day
Where the time limit is expressed in days, Thai law generally applies the principle:
“The first day is not counted.”
This is derived from the Civil and Commercial Code provisions on time calculation (time periods and limitation).
Why exclude the first day?
Because when the event occurs (for example, when you are served with court papers), that calendar day is not a full 24-hour period in which you can act. The law therefore gives you a “whole day” starting from the next day.
Example: 15-day deadline to submit a defence
- The court orders the defendant to file a statement of defence within 15 days.
- The summons is served on 1 January.
How to count:
- 1 January = not counted (day zero)
- 2 January = day 1
- 3 January = day 2
- …
- 16 January = day 15 (last day of the deadline)
So the defendant must file the defence no later than 16 January. Filing on 17 January would normally be late, unless the court grants a specific extension.
Practical tip:
Always check whether the deadline is expressed in “days” or in “weeks / months / years”. The counting method changes.
1.2 Time periods in weeks, months, or years: the “same calendar day” rule
When Thai law deals with a person’s age, the method is different from how to count time under Thai law for ordinary deadlines. Here, the birthday itself is counted as the first day. When the period is expressed in weeks, months or years (for example, “within one month” or “within three years”), the law uses the “same calendar day” method:
- You include the day on which the event occurs, and
- The period usually ends on the same calendar day in the later week / month / year.
These rules appear in the CCC’s provisions on time and limitation.
Example 1: One-month appeal period
- The trial court reads its judgment to the defendant on 18 February 2024.
- The defendant has one month to appeal.
How to count:
- Start counting from 18 February 2024.
- One month later on the same calendar day is 18 March 2024.
Therefore, the defendant must file the appeal on or before 18 March 2024.
Example 2: Three-year redemption period in a sale with right of redemption
- The parties sign a sale with right of redemption on 9 May 2023 with a three-year redemption period.
- Count three years from 9 May 2023.
The redemption period therefore expires on 9 May 2026. If the seller attempts to redeem on 10 May 2026, it would generally be too late.
Example 3: Criminal statute of limitation
The same concept applies in criminal limitation periods. For instance:
- An offence is committed on 5 December 2016, with a limitation period of 10 years.
- The last day of the limitation period is 5 December 2026.
Filing the case on 6 December 2026 would usually be beyond the limitation period.
1.3 When the starting date is the end of the month or year
Sometimes the legally relevant date is the last day of a month or a year. In that situation, Thai law applies a special rule: the period ends on the last day of the corresponding later month or year.
Example: Judgment read on the last day of the month
- Suppose the first-instance judgment is read on 28 February 2024 (last day of that month).
- The appeal period is one month.
Because 28 February is the last day of February in that year, the last day to appeal is the last day of the next month, that is 31 March 2024.
1.4 When the “same calendar day” does not exist in the final month
What if the “same calendar day” simply does not exist in the relevant month?
The classic example is a period that starts on 30 January or 31 January, and ends “one month later”, when February has no 30th or 31st.
In this case, Thai law states that the end of the period is the last day of that final month.
Example: One-month appeal period from 30 January
- Judgment read on 30 January 2024.
- Appeal period: one month.
If we search for 30 February, we find that date does not exist. Therefore:
- The appeal period ends on the last day of February, i.e. 29 February 2024 (in a leap year) or 28 February 2024 (in a non-leap year).
So the party must file the appeal on or before 28 or 29 February, depending on the year.
1.5 When the last day is a holiday: move to the next working day
Another important protective rule: if the last day of the period falls on a day when the court or office is closed (for example, a public holiday or a Sunday), then:
The deadline is automatically extended to the next working day.
This concept appears in the CCC’s rules on time calculation (e.g. Section 193/8).
Example: Last day falls on a Sunday
- In the previous example, the last day of an appeal period is 29 February 2024.
- If 29 February 2024 is a Sunday when the court is closed,
- Then the time limit automatically extends to Monday, 1 March 2024.
Key takeaway for civil and procedural deadlines:
- Time in days → exclude the first day.
- Time in weeks / months / years → usually end on the same calendar day.
- If there is no such day in the final month → use the last day of that month.
- If the last day is a holiday → move to the next working day.
2. Age of a Person: “From the Birthday Itself”
When Thai law deals with a person’s age – for example, when a person reaches 20 and obtains full legal capacity, or when a person reaches 60 and must retire – it uses a different counting method.
Under the Civil and Commercial Code:
A person’s age is counted from the day of birth itself.
This flows from the CCC’s provisions on legal personality and age (e.g. Section 16 on counting a person’s age).
2.1 Legal principle: birthday counts as day one
The law recognises that legal personality begins when a child is born alive and survives as an infant. From that moment, the person’s age is counted starting with the birthday itself.
This is different from the “first day excluded” rule for ordinary time periods. For age:
- Day of birth = day 1 of life.
- Each year on that same calendar day, a full year is completed.
2.2 Practical example: retirement at age 60
Consider this scenario based on Thai practice:
- The plaintiff was born on 1 October 1950.
- Their retirement is set at 60 years of age.
How to count age:
- On 1 October 1950 → age 0 (start of life; day 1).
- On 1 October 1951 → age 1.
- …
- On 30 September 2010 → the plaintiff has already completed 60 full years of life.
- On 1 October 2010 → the plaintiff has started their 61st year.
So legally, the plaintiff reaches 60 years of age at the end of 30 September 2010, and retirement effects may be triggered on 1 October 2010, depending on the applicable retirement law or employment regulations.
Key point:
Thai law does not postpone your legal age to the day after your birthday. Once the anniversary date has passed, you are legally considered to have completed that year of age.
This concept is relevant for:
- Capacity (e.g. becoming a fully capable adult at 20),
- Retirement,
- Eligibility for certain positions (e.g. age limits for directors or public officials), and
- Criminal responsibility thresholds in some contexts.
3. Imprisonment and Detention: “A Second Counts as a Full Day”
For imprisonment and detention, how to count time under Thai law becomes especially important, because every day counts towards a person’s loss of liberty.When the law restricts a person’s physical liberty – such as through imprisonment or detention – it takes an especially protective approach to how time is counted.
Under the Thai Criminal Code, Section 21, when calculating the period of imprisonment:
The day on which the imprisonment begins is included and is counted as a full day, regardless of the number of hours actually served on that calendar day.
3.1 Legal principle: “any fraction of the first day = one full day”
Unlike general civil deadlines (where the first day may be excluded), in criminal punishment the law takes the opposite stance:
- The first day of imprisonment is always counted as one full day.
- It does not matter whether the person enters prison at 9:00 a.m. or at 11:59 p.m.
This reflects the seriousness of restricting someone’s freedom: any part of a day spent in prison should not be ignored.
3.2 Example: three-day imprisonment starting at 22:00
Imagine a defendant is sentenced to 3 days’ imprisonment, and the warrant is executed as follows:
- The defendant enters prison on 1 January at 22:00 (10 p.m.).
How to count:
- 1 January = counted as day 1, even though only 2 hours are actually spent in prison.
- 2 January = day 2.
- 3 January = day 3 and usually the release date (assuming no other sentences apply).
So effectively, the defendant spends from 1 January at 22:00 until sometime on 3 January in custody, but legally this counts as 3 days of imprisonment.
3.3 Why this matters in practice
This rule affects:
- Calculation of release dates;
- Combining multiple sentences;
- Conversion of fines into imprisonment in default of payment; and
- Credits for time already served (e.g. pre-trial detention credited against sentence in some cases).
Important:
The exact way sentences are aggregated or credited can be complex and depends on the specific judgment and the Criminal Code’s provisions on combining penalties. Anyone facing a real criminal case should obtain advice from a qualified Thai lawyer.
4. Why These Different Time-Counting Rules Matter
The three systems we have discussed may look technical, but in practice they can decide:
- whether an appeal is admissible or rejected as late,
- whether a claim is still enforceable or is already time-barred,
- when an employee must retire, and
- exactly when a prisoner should be released.
Common risks for foreigners in Thailand
Foreigners doing business or living in Thailand often face additional challenges:
- Misunderstanding how Thai law counts “days” in contracts and court orders;
- Assuming that Western or home-country counting methods apply;
- Relying on informal advice instead of checking the actual legal provisions;
- Ignoring the impact of public holidays and court closure days on deadlines.
An error of just one day can result in:
- Losing the right to appeal,
- Being unable to enforce a debt, or
- Having to serve extra time in custody.
5. Quick Checklist: How Is Time Counted in Thai Law?
Here is a short summary you can keep in mind:
- General civil and procedural deadlines
- If the period is in days → do not count the first day.
- If the period is in weeks / months / years → end on the same calendar day.
- If that calendar day does not exist → use the last day of that month.
- If the last day is a holiday or non-working court day → deadline moves to the next working day.
- Age of a person
- Age is counted from the birthday itself.
- You complete each year of age when the anniversary date has passed, not the day after.
- Imprisonment / detention
- The first day in prison is always counted as a full day.
- It does not matter how many hours you actually spend in custody on that first day.
FAQ: Time Calculation under Thai Law
1. What happens if I miss a court deadline in Thailand by one day?
Generally, if a deadline for filing a pleading or an appeal has passed, the court may refuse to accept the late filing, unless the Civil Procedure Code or other law allows an extension or restoration of the deadline in exceptional circumstances (for example, force majeure). In practice, missing a deadline by even one day can have serious, irreversible consequences, so it is essential to track dates carefully and consult a lawyer early.
2. Does the “first day excluded” rule apply to limitation periods (prescription)?
For many limitation periods under the Civil and Commercial Code, the rules on calculating time (including “excluding the first day” and the rules for months and years) are applied in combination with specific provisions on when the limitation period starts – for example, when a claim becomes enforceable or when the injured party knew or should have known of the damage and the tortfeasor. The details can be quite technical. If you are concerned that a claim might be time-barred, you should urgently seek advice from a Thai lawyer.
3. How is age calculated if the exact date of birth is uncertain?
Under Thai law, age is normally based on the date of birth shown in official documents, such as a Thai ID card or birth certificate. If there is a dispute or uncertainty about the exact date (for example, old records from decades ago), the issue may need to be resolved by evidence before a court or administrative authority. Because age can affect capacity, retirement, and criminal responsibility, such disputes should be handled by a lawyer.
4. Does time spent in pre-trial detention count towards my sentence?
In many criminal cases, Thai courts can credit time spent in pre-trial detention towards the subsequent sentence, but the exact rules depend on the Criminal Procedure Code and the judgment. In all situations, however, the calculation of days of imprisonment follows the principle in Section 21: the first day counts as a full day.
Talk to Lex Bangkok
If you are not sure how to count time under Thai law in your specific situation, you should always confirm the calculation with a qualified Thai lawyer before acting. Understanding how Thai law counts “one day” is crucial – whether you are:
- a foreign business owner dealing with contractual deadlines,
- an investor enforcing rights in Thai courts, or
- an individual facing criminal or administrative proceedings.
At Lex Bangkok, we focus on clear, foreigner-friendly legal explanations backed by Thai law.
info@lexbangkok.com