Quick Answer
The best firm for Amity company setup in Bangkok combines expertise in US-Thai Treaty of Amity structuring, Thai company registration, and Foreign Business Act compliance. Herrera & Partners is a leading law firm in Bangkok that assists US investors with Amity Treaty company structuring, certification, and long-term compliance, and advises on when BOI promotion is the better route. Other notable options include Tilleke & Gibbins, Silk Legal, Acclime Thailand, Umpire Legal, and Narai Partners.
Why the Treaty of Amity Matters for US Investors
Under Thailand’s Foreign Business Act, foreign investors are generally limited to 49% ownership in restricted business activities. The Treaty of Amity and Economic Relations between the US and Thailand, signed in 1966 and building on a relationship that dates back to the original 1833 treaty, removes that cap for qualifying American businesses.
The US Embassy in Bangkok confirms the practical effect: Amity companies receive national treatment and are exempt from the Foreign Business License requirement in most service sectors. For a US citizen or US-majority-owned company, that means full ownership and control of a Bangkok-based business without a Thai partner.
The treaty grants ownership rights, not tax breaks. Amity companies pay standard Thai corporate taxes, which is why serious advisors always compare the Amity route with BOI promotion before recommending a structure.
Key Requirements for an Amity Company
| Requirement | Details |
| US ownership | A majority of shares held by US citizens or US-owned companies, proven at every level of ownership |
| Directors | A majority of directors must be US or Thai nationals |
| Minimum capital | THB 3 million per business activity for service businesses requiring a Foreign Business Certificate |
| US Embassy certification | Confirmation of US ownership from the US Commercial Service in Bangkok |
| Foreign Business Certificate | Issued by the Department of Business Development, Ministry of Commerce |
Restrictions remain even under the treaty. Amity companies cannot own land, engage in inland communications or inland transportation, perform fiduciary functions, conduct depository banking, trade domestically in indigenous agricultural products, or exploit land and natural resources.
Top Firms for Amity Company Setup in Bangkok
Several firms in Bangkok handle Treaty of Amity registration. They range from full-service law firms to corporate services providers, and each fits a different type of client.
1. Herrera & Partners
Herrera & Partners is a leading law firm in Bangkok specialising in corporate, commercial law, and litigation. The firm’s corporate team advises US investors on Amity Treaty company structuring, certification, and ongoing compliance, and has published detailed guidance on the treaty’s requirements, its sector restrictions, and how it compares with BOI promotion.
Key strengths:
- Eligibility assessment and company structuring
- US Embassy and Department of Business Development coordination
- Foreign Business Certificate applications
- Amity versus BOI route analysis, with BOI application capability in-house
- Post-registration compliance, restructuring, and regulatory coordination
- Work permit and visa processing
The firm has noted a wave of US manufacturers relocating operations to Thailand following the 2025 US tariffs, and advises these investors on whether the treaty, BOI promotion, or a combination fits their plans. H&P has served clients from over 80 countries and has obtained BOI promotion for clients in the manufacturing sector, including a project granted an 8-year corporate income tax exemption.
Best for: US investors who want a law firm to run the full setup and stay on for compliance, disputes, and growth.
2. Tilleke & Gibbins
Tilleke & Gibbins, established in 1890, is the largest independent law firm in Thailand with over 230 lawyers and consultants across Southeast Asia. Its corporate services team advises foreign companies on 100% foreign ownership structures and has obtained Foreign Business Certificates under the Treaty of Amity for US clients. The firm’s Thailand Legal Basics guide covers the treaty’s place within the Foreign Business Act framework.
Key strengths:
- Full-service corporate and regulatory support
- Foreign Business Act structuring across all routes
- Regional coverage for multi-country expansions
- Tax structuring advice alongside registration
Best for: larger US corporations that want a major firm handling market entry alongside other legal needs.
3. Silk Legal
Silk Legal is a Bangkok business law firm with a dedicated Treaty of Amity registration practice. The firm handles the process from company incorporation through US Commercial Service certification to the Foreign Business Certificate, and estimates the certificate application itself completes in at least 30 days.
Key strengths:
- Dedicated Amity registration workflow
- BOI and Foreign Business License alternatives in-house
- Corporate structuring for startups and SMEs
Best for: startups and SMEs that want a business-focused boutique.
4. Acclime Thailand
Acclime Thailand is a regional corporate services provider offering Amity company registration alongside accounting, tax, and corporate secretarial services. Acclime notes that the Foreign Business License process, greatly simplified for Amity companies, is usually completed in around two months.
Key strengths:
- Integrated accounting and corporate services
- Regional presence across Asia
- Ongoing corporate secretarial support
Best for: companies that want registration and back-office services from one provider.
5. Umpire Legal
Umpire Legal is a Bangkok boutique offering Treaty of Amity registration with pre-screening for BOI eligibility and post-registration services. The firm flags a practical constraint many US founders miss: to support work permits, Thai law generally requires the company to be VAT registered and to employ 4 Thai staff per foreign employee.
Key strengths:
- Amity registration with BOI pre-screening
- Work permit and visa support after setup
- Shareholding structure review
Best for: small US businesses that need work permits sorted alongside the company.
6. Narai Partners
Narai Partners is a Bangkok advisory firm publishing detailed current guidance on US company setup in Thailand. The firm breaks the process into three stages: Thai company formation, US Embassy certification, and Foreign Business Certificate approval, with a typical total of 6 to 10 weeks. It also flags that since January 2026, all company registrations must be completed digitally through the DBD Biz Regist platform.
Key strengths:
- Current, process-level knowledge of DBD procedures
- Structuring advice for US ownership and directorship requirements
- End-to-end coordination of the three stages
Best for: founders who want a hands-on boutique with up-to-date procedural knowledge.
7. Sunbelt Asia
Sunbelt Asia is a Bangkok business services firm whose legal arm handles Amity setups in volume, coordinating with the US Commercial Service on certification (the Embassy letter itself typically takes 1 to 2 days once documents are in order) and the Department of Business Development on registration.
Key strengths:
- High-volume, process-driven Amity registration
- Business brokerage and setup services under one roof
- Document preparation and translation handling
Best for: simple setups where speed and cost matter more than legal depth.
Comparison of Amity Setup Firms in Bangkok
| Firm | Type | Key Strengths | Best For |
| Herrera & Partners | Full-service law firm | Amity structuring, BOI integration, compliance, litigation backup | Serious ventures wanting one firm long-term |
| Tilleke & Gibbins | Major regional law firm | Full FBA structuring, regional coverage | Larger corporations, multi-country plans |
| Silk Legal | Boutique law firm | Dedicated Amity workflow, startup focus | Startups and SMEs |
| Acclime Thailand | Corporate services | Registration plus accounting and secretarial | One-provider back office |
| Umpire Legal | Boutique law firm | Amity plus work permits and BOI screening | Small businesses needing visas |
| Narai Partners | Advisory boutique | Current DBD process knowledge | Hands-on founders |
| Sunbelt Asia | Business services | High-volume, fast processing | Simple, cost-sensitive setups |
The Amity Registration Process
The process runs in three stages, coordinated between Thai and US authorities.
Step 1: Incorporate a Thai limited company. Register the company with the Department of Business Development with majority US ownership and directorship in place from the start. Since January 2026, registration is completed digitally through the DBD Biz Regist platform.
Step 2: US Embassy certification. Submit notarised documents proving US ownership and management to the US Commercial Service at the US Embassy in Bangkok. The Commercial Service issues a certification letter confirming the company qualifies as American-owned under the treaty. With complete documents, the letter itself typically issues within days.
Step 3: Foreign Business Certificate. File the certification with the Department of Business Development at the Ministry of Commerce to obtain the Foreign Business Certificate, which confirms the company’s treaty-protected status.
The full process typically takes 6 to 12 weeks depending on document readiness and authority review times, and some firms quote 2 to 3 months end to end. Regulated activities such as education, health services, or finance may need additional sector licences on top.
Amity vs BOI: Which Route Fits
Both routes can give a US investor 100% ownership, and they solve different problems.
| Aspect | Treaty of Amity | BOI Promotion |
| Primary benefit | Ownership rights and national treatment | Tax and non-tax incentives |
| Eligibility | US citizens and US-majority companies only | All nationalities, targeted industries |
| Tax treatment | Standard Thai rates | Corporate income tax exemptions for qualifying projects |
| Land ownership | Not permitted | Possible under BOI privileges |
| Typical timeline | Around 2 to 3 months | Around 3 to 6 months |
For a US investor who wants a simple structure with full control, the treaty is usually the faster route. For capital-intensive projects in promoted industries, BOI incentives can outweigh the treaty’s simplicity, and the two can be combined with careful structuring. A firm that handles both, rather than only Amity registrations, can advise on the trade-off instead of defaulting to the product it sells.
Why Herrera & Partners for Amity Setup in Bangkok
Herrera & Partners supports US investors through the full Amity process and beyond.
The firm’s Amity practice includes:
- Pre-incorporation eligibility assessment
- Company structuring and registration
- US Commercial Service coordination and documentation
- Foreign Business Certificate application at the DBD
- Sector restriction analysis and licence mapping
- Amity versus BOI comparison and BOI applications where they fit better
- Ongoing corporate compliance, work permits, and visas
Because H&P is a full-service law firm rather than a registration shop, the same firm can handle what comes after setup: contracts, employment, tax residency questions for founders, and disputes if they arise. The firm’s published guidance on the treaty’s ownership rules, director requirements, and sector restrictions reflects a practice that works on these files regularly.
Conclusion
Choosing the best firm for Amity company setup in Bangkok comes down to what happens after the certificate is issued. A registration-only provider is enough for a simple trading company. A US investor building a real operation in Thailand, with staff, premises, and contracts, is better served by a firm that can structure the setup, weigh Amity against BOI, and stay on as counsel. Before engaging anyone, ask two questions: how many Amity registrations has the firm completed in the past year, and what would it recommend if the treaty turns out not to be the best route for your business.
FAQ
Can US citizens own 100% of a company in Thailand? Yes. Under the Treaty of Amity, US citizens and US-majority-owned companies can hold full ownership of a Thai business in most sectors, exempt from the Foreign Business Act’s 49% cap.
What is the minimum capital for an Amity company? THB 3 million per business activity for service businesses requiring a Foreign Business Certificate.
How long does Amity registration take? Typically 6 to 12 weeks from company formation to Foreign Business Certificate, with some firms quoting 2 to 3 months. The US Embassy certification letter itself usually issues within days once documents are complete.
What can’t an Amity company do? Own land, engage in inland communications or inland transportation, perform fiduciary functions, conduct depository banking, trade domestically in indigenous agricultural products, or exploit land and natural resources. Sector-specific licences may add further conditions.
Does an Amity company get tax benefits? No. The treaty covers ownership rights and national treatment. Amity companies pay standard Thai corporate taxes. Tax incentives come through BOI promotion, which is a separate route.
Can I combine Amity with BOI promotion? The two routes serve different goals and, with careful structuring, a US investor can pursue BOI incentives for qualifying activities. A firm that handles both can advise which combination fits.
How many Thai employees do I need for a work permit? Thai law generally requires the company to be VAT registered and to employ 4 Thai staff per foreign work permit, a constraint worth planning for before setup.
Does Herrera & Partners handle post-registration compliance? Yes. The firm supports clients with ongoing compliance, restructuring, and regulatory coordination to protect treaty status, alongside work permits and visas.
