Best BOI Lawyers in Thailand: 6 Law Firms for Board of Investment Applications

Law firms in Bangkok that handle Board of Investment (BOI) applications include Herrera & Partners, Baker McKenzie, Tilleke & Gibbins, Siam Premier International Law Office, Specter CK & Partners and Lex Bangkok. They range from international firms with more than 240 lawyers in Bangkok to small practices that handle BOI filings alongside company registration and licensing. BOI promotion can bring a corporate income tax exemption of up to 13 years, so the activity category your lawyer secures shapes the value of the whole project.

What is BOI promotion in Thailand?

BOI promotion is a package of tax and non-tax incentives the Thailand Board of Investment grants to companies running approved activities, under the Investment Promotion Act B.E. 2520 (1977). Promoted activities fall into groups that set the length of the corporate income tax (CIT) exemption:

• A1+: 10 to 13 years, with no cap on the exempt amount.
• A1: 8 years, with no cap.
• A2: 8 years.
• A3: 5 years.
• A4: 3 years.
• B: 1 to 5 years, granted only through merit-based criteria.

Every group also qualifies for import duty exemptions on machinery and on raw materials used in export production. Merit-based incentives add exemption years for spending on R&D, training and local supplier development, and for projects in 20 low-income provinces.

The non-tax side matters just as much for foreign investors. A BOI-promoted company can be 100% foreign-owned in most promoted activities, own land for the project, bring in skilled foreign workers and remit money abroad in foreign currency.

How the BOI application process works

The BOI process runs in 8 steps:

1. Preparation. The investor confirms the activity is on the BOI’s promoted list and gathers the application documents.
2. Submission. Most applications go online through the BOI’s e-Investment Promotion system.
3. Officer meeting. The applicant presents the project to the assigned BOI officer within 10 working days of submission.
4. Review. The BOI assesses the project within a period set by investment size: 40 working days up to THB 200 million, 60 days up to THB 2,000 million, and 90 days above that.
5. Notification. The BOI sends the result within 7 days of approving the meeting minutes.
6. Acceptance. The company must accept the promotion within 1 month of the notice.
7. Certificate application. The company applies for the promotion certificate, with supporting evidence, within 6 months.
8. Certificate issue. The BOI issues the certificate within 10 working days of receiving complete evidence.

After certification, the company files progress reports and must meet the investment, employment and timeline conditions attached to its promotion to keep its incentives.

6 law firms that handle BOI applications in Bangkok

All 6 firms below have a Bangkok office and prepare BOI applications for foreign and Thai investors.

1. Herrera & Partners (H&P)

Herrera & Partners is a Bangkok firm specialising in corporate, commercial law and litigation, with clients from more than 80 countries. Its BOI team designs applications, prepares presentations to the BOI and sets up promoted companies. Its lawyers have spoken alongside BOI Executive Directors at investment summits and at a 2023 BOI webinar.

Strengths

• Obtained BOI promotion in September 2022 for a special polymer products manufacturer under category 6.5.1, securing an A2 corporate income tax exemption of 8 years for the client.
• Has worked directly with BOI officers in Thailand and abroad, and handled a 2025 BOI application for a software development company.

Limitations

• Works from a single Bangkok office, so provincial projects run from the capital.
• Working languages are Thai, English and Spanish.

Best fit for: foreign manufacturers and technology companies that want one firm for the BOI application, company set-up and post-approval compliance work.

2. Baker McKenzie

Baker McKenzie opened its Bangkok office in 1977 and has around 240 lawyers and specialists there, the largest legal team in Thailand. Its tax and corporate groups track BOI policy closely and publish updates on new promotion measures, from electric vehicle incentives to promotions for software, digital platforms and digital content.

Strengths

• Covers BOI work for relocations of entire operations, including manufacturing plants, regional headquarters and R&D centres moving to Thailand.
• Runs a Japan Advisory Group in Bangkok, which supports Japanese investors through promotion, incorporation and operations.

Limitations

• The office is built for multinationals, financial institutions and large Thai companies, which suits large projects more than small BOI filings.
• Work runs through a large team, so day-to-day contact may sit with associates rather than partners.

Best fit for: multinationals planning large manufacturing, regional headquarters or R&D investments that need BOI, tax and corporate advice from one firm.

3. Tilleke & Gibbins

Tilleke & Gibbins was established in Bangkok in 1890 and is the largest independent law firm in Thailand, with more than 250 lawyers and consultants across 6 Southeast Asian countries. BOI applications sit within its corporate and commercial group, which handles foreign investment licensing and company set-up.

Strengths

• Its corporate lawyers advise foreign companies on applications for BOI investment promotion privileges together with the matching business incorporation in Thailand.
• Covers foreign business licence applications in the same team, which helps when part of a project falls outside the BOI’s promoted list.

Limitations

• The firm’s client base leans towards multinationals and high-growth companies, which suits larger projects more than early-stage ventures.
• BOI work sits inside a broad full-service practice spanning IP, disputes, regulatory and tax work across the region.

Best fit for: foreign companies that want BOI promotion handled alongside licensing, IP protection and regional expansion across Southeast Asia.

4. Siam Premier International Law Office

Siam Premier International Law Office is an independent Thai firm established in 1990, with 90 lawyers in Bangkok. Its foreign direct investment practice advises on BOI promotions and BOI applications, and on the incentives available under Thai investment laws. It’s a member of the American, British, Australian and Singapore chambers of commerce in Thailand.

Strengths

• Represents clients in negotiations with the BOI, the Ministry of Commerce and the Industrial Estate Authority of Thailand during approval processes.
• Prepares formal notices and submissions to government authorities, and regularly works alongside international firms on cross-border transactions.

Limitations

• The practice centres on corporate transactions, major projects and regulatory matters, which suits established companies more than first-time founders.
• Working languages are English and Thai.

Best fit for: companies whose project needs approvals from the BOI and the Industrial Estate Authority at the same time, such as a factory in an industrial estate.

5. Specter CK & Partners

Specter CK & Partners is a Bangkok firm with teams in Phuket, Pattaya and Koh Samui. Its BOI practice covers eligibility assessment, application preparation, BOI liaison and post-approval compliance, and it also sets up US Treaty of Amity companies and handles foreign business licences.

Strengths

• Prepares project proposals, financial models and investment plans for the application, and answers BOI officers’ questions during review.
• Handles post-approval reporting, monitoring of investment and employment conditions, and work permits and visas through the BOI’s One-Stop Service Center.

Limitations

• BOI work is one service in a broad practice that also covers litigation, property, immigration and family law.
• Its corporate and BOI team is part of a 20-person firm, so very large, multi-site projects may stretch its capacity.

Best fit for: small and mid-sized foreign investors, including those based outside Bangkok, who want BOI work combined with visas and company administration.

6. Lex Bangkok

Lex Bangkok is a Bangkok law firm serving international businesses, with a headquarters in Bueng Kum and a Sukhumvit branch. Its team works in English, Thai and Japanese, and BOI registration sits in its regulatory practice alongside foreign business licences, factory licences and FDA registration.

Strengths

• Runs BOI applications end to end, from eligibility checks and incentive-tier selection to the application package, BOI officer liaison, incorporation and annual compliance reporting.
• Its corporate work includes the expansion of a chemical manufacturing facility valued at more than THB 1 billion.

Limitations

• A small team led by managing partner Ryutaro Sato, with 4 named lawyers and counsel.
• BOI registration is one item in a wide service menu that also covers accounting, translation and notary work.

Best fit for: Japanese and other foreign manufacturers that need BOI promotion, a factory licence and company set-up handled by one small team.

Recap table

How to choose a BOI lawyer

What to check before hiring

• Activity classification. The group your activity lands in sets the length of the tax exemption. Ask how the lawyer would classify your project and what merit-based incentives could add years.
• Financial modelling. The application needs investment plans and financial projections. Ask whether the firm prepares them or works with your accountants.
• Post-approval compliance. Incentives depend on meeting investment, employment and reporting conditions. Ask who tracks those deadlines after the certificate is issued.
• Alternatives. Some activities fall outside the promoted list. A good BOI lawyer should also advise on the Treaty of Amity for US investors or a foreign business licence.
• Language and access. Ask who will present your project to the BOI officer and which language your day-to-day contact works in.

Warning signs

• Guaranteed approval. The BOI decides each application on its merits after its review period, so no lawyer can promise an outcome.
• Incentives quoted before classification. A firm that promises a specific number of tax-free years before reviewing your activity against the promoted list is guessing.

FAQ

How long does BOI approval take?

The BOI reviews a complete application in 40 working days for investments up to THB 200 million, 60 days up to THB 2,000 million and 90 days above that. Acceptance, certification and company set-up add further time.

Can a BOI-promoted company be 100% foreign-owned?

Yes. BOI promotion allows full foreign ownership for most promoted activities, which is one of the main reasons foreign investors apply instead of setting up a Thai majority company.

What is the minimum investment for BOI promotion?

Most promoted activities require a minimum investment of THB 1 million, excluding land and working capital. Specific activities set higher thresholds, so the requirement depends on the category.

What happens after BOI approval?

The company accepts the promotion within 1 month, applies for the promotion certificate within 6 months, then files progress reports and meets the investment and employment conditions attached to its promotion.

What is the difference between BOI promotion and the Treaty of Amity?

BOI promotion grants tax and non-tax incentives to approved activities and is open to investors of any nationality. The Treaty of Amity gives US investors ownership rights for most business activities without the BOI’s tax incentives.