Leaving to Join a Competitor in Thailand: Non-Compete Clauses, Trade Secrets, Customer Solicitation and Taking Data

You have just received an offer from a competitor, but your employment contract says "no work for competitors for 2 years". Or you are an employer who wrote a clause like that and wants to know whether it will hold. The question is usually answered as if it were one issue, when the law actually has at least four separate ones: the non-compete, trade secrets, non-solicitation of customers and staff, and taking data. Each has a different source, test and consequence.

This guide focuses on the non-compete itself and on keeping the four apart. If the company has already lost a customer list, see our guide on former employees taking customer lists. If the issue is a side business competing while the person is still employed, see our guide on conflicts of interest.

Short Answer

As a rule, a person who has left is free to work anywhere. A non-compete is an exception that needs a contract behind it, and a court will give it effect only to a fair and reasonable extent. Trade secrets, customer non-solicitation and data removal are separate matters: you may be entitled to join a competitor and still be in breach if you take files or a customer list with you.

Legal Framework Section 5 of the Unfair Contract Terms Act B.E. 2540 provides that a term restricting a person's freedom to practise an occupation or business, where it burdens that person more than is normally foreseeable, is enforceable only to the extent that it is fair and reasonable. Section 14/1 of the Labour Protection Act B.E. 2541 is a further route for challenging unfair terms in an employment agreement. Trade secrets are governed by the Trade Secrets Act B.E. 2545 (definition in Section 3, infringement in Section 6, injunctions in Section 8). Penalty clauses are in the Civil and Commercial Code, Sections 379 to 383. Customers' personal data falls under the Personal Data Protection Act B.E. 2562.

Our Practical View A non-compete that is wide in time, area and kind of work is the weakest tool an employer has, and a risk employees often fear more than they should. By contrast, what an employer can prove most easily, and what employees get wrong most often, is taking files out. Employees should worry more about data removal than about the new company's name. Employers should put their effort into confidentiality and narrow non-solicitation, not a broad non-compete.

Hypothetical Bua is a sales supervisor at a farm-equipment distributor in Khon Kaen, handling retailers across upper Isan. Her contract bars work in "similar businesses" anywhere in Thailand for 2 years and sets a lump-sum penalty. A competitor in Udon Thani offers her a job. While she is deciding, she forwards some quotations and a wholesale price list to her personal email "for reference". We use this case throughout and call her former employer "the company".

1. Can I Join a Competitor After Resigning?

If there is no restriction in the contract, yes. General knowledge, skills and experience gained on the job are the employee's own, not the employer's secret.

If there is a non-compete, it is neither automatically enforceable nor automatically void. A court applies Section 5 of the Unfair Contract Terms Act, looking at these factors.

A court may give effect to part of a term, or to the term only to the extent that is fair, rather than striking out the whole clause. We cannot say in advance how far a court would cut it back. Section 14/1 of the Labour Protection Act adds a route for arguing that an employment term is unfair, and again the result depends on the facts.

In the hypothetical, Bua's clause covers the whole country and "similar businesses", while the company sells in upper Isan. A court would likely narrow it. But if the new job is selling the same products to the same group of retailers in Udon Thani, a real risk remains. Bua should not conclude on her own that the clause is unenforceable.

2. Four Obligations to Keep Apart

Read the table this way. The first and third rows answer where the employee may work and whom the employee may approach. The second and fourth answer what the employee may take. An employee can win on the non-compete and still lose on trade secrets, and the reverse.

3. Taking Data Out: Personal Email and Copied Customer Lists

Three behaviours are common shortly before an employee leaves: forwarding files to personal email or apps, copying customer lists to a USB drive, and photographing system screens. All three leave traces in system logs, and the logs are often the key evidence.

• Trade secrets. If the file meets the Section 3 test, taking or using it without consent may be infringement under Section 6. A list that every employee can open, with no confidentiality agreement, is hard to call secret. For the detail, see the guide on former employees and customer lists.
• Personal data. Names, phone numbers and purchase histories of customers who are individuals are personal data. The company is the controller, with security duties under PDPA Section 37. An employee who moves such data outside company systems without permission exposes the company to a data incident and may be liable to the company or the data subjects. See our PDPA guide for HR.
• Computer Crime Act. The Computer Crime Act B.E. 2550, Sections 5 to 7, concerns accessing a computer system or data without right where there is access protection. An employee using their own login in the ordinary way and then sending a file out may not fit these provisions. Continuing to log in with old credentials after leaving, or entering areas not granted, carries more risk. For that reason it should not be the lead allegation, and an employer should not report it merely to apply pressure.

Some employees keep files "for self-protection", for example proof that they were told to work overtime. Choose only documents about your own rights: payslips, the contract, the termination letter and messages sent to you. Do not take customer files, prices or internal reports. If you genuinely need something as evidence in a dispute, consult a lawyer first.

In the hypothetical, sending quotations and the wholesale price list to a personal email can be read as preparing to use them at the competitor, even if they were never used. It is an issue that can become bigger than the non-compete.

4. Penalty Clauses: A Court Can Reduce Them

Non-competes often come with a penalty, an agreed sum payable on breach. Sections 379 to 383 of the Civil and Commercial Code provide the framework.

• Sections 379 to 381: a debtor may agree to pay a penalty on non-performance or defective performance, with consequences that differ between the two. If the creditor accepts performance, it must reserve the right to the penalty at the time of acceptance, otherwise the right may be lost (Section 381, paragraph 3).
• Section 383: if the penalty is disproportionately high, a court may reduce it to a reasonable amount, taking into account all the creditor's legitimate interests, not only financial ones.

Practical points:

1. The court must first accept that the non-compete is enforceable. The penalty follows the breach of that term. If the court narrows the restriction, the penalty attaches only to what remains.
2. A single lump sum unrelated to the role or foreseeable loss is easier to reduce than a figure calculated with reasons.
3. An employer cannot simply deduct a penalty from the final pay, because Section 76 of the Labour Protection Act limits deductions from wages. See the same point in our guide on training bonds.

5. Before You Resign: What an Employee Should Do

Start by reading the whole employment contract and work rules: non-compete, non-solicitation, confidentiality and penalties. Then follow the list below. Poor handover is a separate issue; our guide on employees who resign without handover is written from the employer's side but shows what a company will check.

• Return things. Return devices, cards, keys and paper files, and have access removed with IT or HR. Obtain a handover record signed by both sides.
• Do not forward files. Not to personal email, LINE or cloud storage, and no photographs of system screens. If personal files are mixed in on your device, ask for permission before taking them.
• Keep a written record of what you retain. If you must keep documents about your own rights, such as the contract and payslips, list them in writing and let HR know.
• Do not rebuild data from memory. Typing a customer list from memory into a spreadsheet for the new employer carries the same risk as copying.
• Be open with the new employer. If there is a non-compete or non-solicitation clause, have a lawyer read it before you accept, and do not let the new employer assume you can bring customers.
• Do not contact former customers to move them. Not while a non-solicitation promise runs, and be careful even if a customer contacts you first.

6. What an Employer Can Realistically Enforce, and How to Draft

Before drafting, an employer should ask what needs protecting, from whom and until when, instead of using one template for every employee.

• Hardest to enforce. A multi-year, nationwide, industry-wide ban on employees at every level with no compensation.
• Better prospects, though never guaranteed. Short non-solicitation of customers the employee actually handled; non-solicitation of staff; confidentiality terms naming the types of information and how it is returned; and a non-compete limited to senior roles, a defined area and time, with compensation for the restricted period.
• What you need after an incident. System access logs, a list of exported files, a signed handover, a demand letter sent promptly, and evidence that the information was actually used.

Sample clause (narrow; adjust to the actual role and business, and have a lawyer review it before use)

Clause __ Non-solicitation of customers and staff after employment ends
1. For ___ months after the employment ends, the Employee will not
   contact any customer whom the Employee handled or about whom the
   Employee received material information in the 12 months before the
   end of employment, in order to offer goods or services that compete
   with the Company's. (The customer list is Annex A, which the Company
   updates in writing.)
2. Within the same period, the Employee will not induce any employee
   of the Company to leave and work for the Employee or a new employer.
3. This clause does not prevent the Employee from working for another
   employer, and does not prevent dealing with a customer who contacted
   the Employee without solicitation, unless the Company's confidential
   information is used.
4. Confidential information, such as wholesale price lists, costs and
   the customer list in Annex A, will be returned and all copies deleted
   within 7 days after employment ends, with written confirmation.
5. On breach, the penalty is ___, which the parties agree is a
   reasonable estimate of loss and does not prevent a court from
   considering a reduction under Section 383 of the Civil and
   Commercial Code.
6. This clause applies only to the position of ____, which has access
   to the information in clause 4.

If an employer wants a full non-compete for a senior role, it should set a reasonably short period, name the area and the kind of work that really competes, and consider compensation for the restricted period. A narrow clause that can explain what it protects has a better chance under Section 5 than one copied from a generic form. After an incident, do not sue first. Send a letter setting out the concern, ask for the data to be returned and deleted, and preserve the evidence described in section 3.

7. Checklists

For an employee about to resign

• Read the whole contract and work rules and know whether there is a non-compete, non-solicitation, confidentiality term or penalty
• Have a lawyer review any clear restriction before accepting the competitor's offer
• Return devices, cards, documents and system access, with a signed handover record
• Do not forward files, copy customer lists or photograph system screens
• Keep a written list of any documents you retain, limited to those about your own rights
• Do not contact former customers to move them and do not recruit colleagues

For an employer drafting the restriction

• Keep confidentiality, non-solicitation and non-compete as separate clauses
• Limit the non-compete to roles with key information, a short period and the area that really competes
• Consider compensation for the restricted period and set the penalty in proportion to foreseeable loss
• Keep a register of confidential information, restrict access and keep system logs
• Have an exit process that returns assets, closes access and has the employee confirm deletion in writing
• Check that the company's own collection and use of customer data complies with the PDPA

Further Reading

• Former employees taking customer lists: when a list has already left and the company must gather evidence
• Side businesses that compete with the employer: restrictions while the person is still employed
• Training bonds and resignation: penalties, wage deductions and court reduction
• PDPA for HR work: employee and customer data the company holds
• Employees who resign without handover: handover, returning devices and cutting access
• HR documents service: clauses, work rules and exit procedures

Joining a competitor is not wrong in itself, but taking data with you is where employees most often go wrong, and a clause that is too wide is where employers most often lose.

We help employees review their contracts and restrictions before they decide to move, and help employers draft confidentiality terms, non-solicitation clauses and exit procedures that are narrow and as enforceable as the law allows. For an initial consultation, call +66 92 254 2045 or send us the details. See also HR documents and labor law.

This guide is published by Suwanvara Law Firm — a Khon Kaen law firm established in 1986. General information only, not legal advice on a specific matter.