Can a sick-leave certificate be backdated? What a doctor can and cannot issue

You were ill yesterday but only see the doctor today. Can the certificate be backdated? What Thai labour law says, what the doctor can write, and the right way to ask.

About 5 min readUpdated 20 September 2026
A stethoscope and a sheet of paper on a desk

A common situation: you spent two days ill at home, and once you're better your employer asks for a medical certificate. Can the doctor backdate it? No. A doctor cannot date a certificate earlier than the examination or certify symptoms they did not see. There are still things the doctor can legitimately do, and they are usually enough for HR. Below is what can and cannot be done.

Key takeaways

  • A doctor can only certify what is found on the day of the examination. Backdating is issuing a false document under Medical Council regulations.
  • What can be done: record that 'the patient reports symptoms since [date]', together with today's findings and an opinion on rest from the examination date onwards.
  • Under Thai labour law you may take sick leave for as long as you are genuinely ill; an employer may ask for a certificate for leave of 3 working days or more, and if you cannot provide one you may explain instead.
  • The best approach is to see a doctor on the first day you are ill, especially if you expect to be off for several days.

Why a certificate cannot be backdated

A medical certificate is a doctor's statement of facts found on examination. The Medical Council's professional ethics regulations state clearly that a practitioner must not issue a false certificate. Dating the examination on a day it did not happen, or certifying that a patient had symptoms on a day the doctor did not see them, is therefore not possible at any clinic.

Every clinic and hospital in the country works to this standard. It protects both patients and employers, because a certificate can only be trusted if it comes from a real examination.

What the doctor can write

If you come today, the doctor examines your current condition and can record the history you give in the form 'the patient reports fever and sore throat since 19 September', which is different from certifying that the doctor saw those symptoms. The doctor then states the diagnosis or findings today and an opinion on how many more days of rest are advisable from the examination date.

If there are still signs of illness, such as an inflamed throat, swollen tonsils or abnormal breath sounds, the doctor records those findings, which makes the document consistent with your account. Most HR departments accept a certificate in this form because the real examination date and the doctor's opinion are clear.

Good to know: If you have evidence of earlier treatment, such as a pharmacy receipt, an ATK result or a photo of your symptoms, bring it. The doctor can use it when recording your history, even though it is not a backdated certification.

What labour law says

Section 32 of the Labour Protection Act allows employees to take sick leave for as long as they are genuinely ill. For sick leave of 3 working days or more, the employer may ask for a certificate from a first-class modern-medicine practitioner or a government health facility, and if the employee cannot provide one they must explain to the employer.

In other words, the law does not require a certificate for 1–2 days of sick leave, but a company's own rules may be stricter. If your company asks every time, the safest approach is to see a doctor on the first day you are ill.

What to do when you know you'll need a certificate

  • See a doctor on the day you are ill, or at the latest the next day while you still have symptoms
  • Describe your symptoms honestly, including when they started and what you have already done
  • Say at registration that you need a certificate and whether your employer wants anything specific, such as the number of rest days or the diagnosis
  • Check the name, date and number of days on the document before leaving the clinic
  • If you are not better when the rest period ends, come back for a re-assessment and a further certificate

Cost and timing

A sick-leave certificate is issued as part of a normal consultation; you pay for the consultation and any medication as usual. See the prices page and the general consultation service. The clinic is open until 8 pm on weekdays, so you can come after work.

Frequently asked questions

The doctor can examine you and issue a document based on today's findings, recording the history you describe, but cannot certify that you were ill yesterday or backdate it. If no signs remain, the document may not be able to state a diagnosis.

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Sources

  1. Labour Protection Act B.E. 2541 (1998), Section 32 (sick leave) Department of Labour Protection and Welfare
  2. Medical Council Regulations on Professional Ethics, 2006 The Medical Council of Thailand

This content is general information and does not replace an examination, diagnosis or personal advice from a doctor. Published 20 September 2026

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