If you've ever talked to a Thai accountant about BOI promotion, you've probably heard sentences like "if you qualify for A1 you get an 8-year tax holiday, no cap" and then immediately wondered: okay but what does that actually mean? What tax am I not paying? For how long? Starting when? And what happens after?
This article answers those questions, tier by tier. The pyramid below is the same one we keep on the homepage — it's the map. The detailed explanations after it are the legend.
A1+ to B activity groups — every incentive a foreign-owned Thai entity can claim, with caps explained.
- BOI
- Board of Investment of Thailand — the agency that grants promotion (tax holidays + non-tax benefits) to qualifying projects.
- Tax holiday
- A period (3 to 13 years depending on the activity group) during which the promoted Thai entity pays 0% Corporate Income Tax instead of the base 20%.
- No cap
- The exemption has no monetary ceiling — every baht of profit during the holiday is exempt.
- Capped
- The total exemption is limited to the value of your project investment (capex excluding land & working capital). Once you've used it, you return to base Corporate Income Tax.
- EEC
- Eastern Economic Corridor — a Thai investment zone (Chonburi, Rayong, Chachoengsao) with extra incentive stacking.
- R&D
- Research & Development — qualifying R&D spend earns merit add-ons on top of the base holiday.
What "tax holiday" actually means
Thailand's base Corporate Income Tax rate is 20% of net profit, filed annually on form PND.50 within 150 days of fiscal year-end. A BOI "tax holiday" doesn't change your obligation to file — you still submit PND.50 — but the rate that applies to the income from your promoted activity is 0% instead of 20% for the length of the holiday.
Three things to understand about that 0% rate that most quick summaries skip:
- The clock starts at first revenue. Not on the day the BOI promotion is granted, and not on the day you incorporate. The years count from the date your promoted activity generates its first baht of revenue. If you spend two years in build mode before launch, you haven't burned any of your tax holiday.
- The holiday only covers the promoted activity. If your company has two revenue streams — one BOI-promoted (say, software development), one not (say, in-store retail) — the 0% rate only applies to the promoted activity. The non-promoted revenue is taxed at the normal 20%. You'll need separate cost accounting between the two from day one to defend the split.
- You still file PND.51 (half-year) and PND.50 (annual). You just compute the tax due as zero for the promoted income. Withholding tax on dividends paid out of exempt profits is also reduced or zero depending on the recipient's residency.
Worked example: an A1 startup over 8 years
Imagine a US-founded SaaS company that qualifies for Group A1 (knowledge-based / high-tech) under BOI Category 8.1.1 software promotion. It launches mid-2026, scales to ฿50 million in net profit annually by year 3, and holds that profit level for the rest of the holiday. Here's what the holiday is actually worth:
Group A1 · 8-year tax holiday · no limit
- Base Corporate Income Tax rate
- 20%
- Years of 0% rate
- 8
- Net profit / yr (years 3–8 steady state)
- ฿50,000,000
- Total profit over the 8-yr holiday
- ฿~300,000,000
- Tax that would have been paid @ 20%
- ฿~60,000,000
- Tax actually paid
- ฿0
- Direct cash saved over the holiday
- ฿~60M
After year 8 the company resumes paying 20%. Merit measures (R&D spend, HR, EEC zone) can extend the 0% rate by another 1–3 years, or add a 50%-rate stack on top.
That ~฿60 million figure is real cash — the difference between paying 20% Corporate Income Tax and 0% on the same profit stream. Compounded into the company at 0% reinvestment cost of capital, the present value to the founders is even higher.
"Capped" vs "uncapped" — the math nobody explains
For Groups A2 through A4, the holiday is "capped." The cumulative tax you'd otherwise have paid is summed up and stopped at the level of your project investment (the BOI's defined capex base — typically machinery, equipment, software, fit-out — excluding land cost and working capital).
Worked example: a Group A3 company with ฿100 million project investment, making the same ฿50M/year net profit:
Group A3 · 5-year tax holiday · limited to investment value
- Project investment (the limit)
- ฿100,000,000
- Base Corporate Income Tax rate
- 20%
- Years of 0% rate
- 5
- Net profit / yr (steady state)
- ฿50,000,000
- Year 1 · would-have-been tax @ 20%
- ฿10M
- Year 2 · cumulative would-have-been tax
- ฿20M
- Year 3 · cumulative
- ฿30M
- Year 4 · cumulative
- ฿40M
- Year 5 · cumulative
- ฿50M
- Limit (฿100M) reached → resume 20%
- Year ~10
In high-profit scenarios the limit can bind before the holiday years run out — effectively shortening the exemption. Lower-margin businesses get the full 5 years and may still have unused limit left over.
So "5 years · capped" doesn't always mean 5 years of zero tax. If you're highly profitable per baht of investment, the cap can bind early. If you're lower-margin, you'll get the full 5 years and still have unused cap when the holiday ends. The cap is a "whichever comes first" condition, not a fixed multiplier.
Per-tier deep dive
Group A1+ — Strategic advanced technology (10–13 years · no cap)
The tip of the pyramid. Reserved for projects of national strategic importance: semiconductor fabrication, biotech research, EV battery cell production, certain frontier-tech R&D. Project committee approval at the Cabinet level. Realistically not the tier most foreign founders will land in — but if you're doing chip design, EV manufacturing, or genomics, you should be applying here. The 10–13-year range is BOI's discretion depending on R&D intensity.
Group A1 — Knowledge-based / high-tech (8 years · no cap)
This is where most software, SaaS, fintech, and digital-first foreign-founded companies land — specifically Category 8.1.1 "software promotion" with the right capex and engineer headcount. The 8-year, uncapped holiday is the most attractive tax incentive available to a typical tech founder in Thailand. Combined with merit add-ons (R&D spend, HR, training), the effective tax holiday can stretch past 10 years.
Group A2 — Advanced infrastructure / national importance (8 years · capped)
Renewable energy projects (large-scale solar, wind), advanced material manufacturing, regional distribution hubs, certain logistics infrastructure. Same headline 8-year holiday as A1, but with the capex cap. For high-capex, lower-margin businesses the cap rarely binds before year 8 — so it functions like uncapped. For high-margin operators, the cap can bind early.
Group A3 — Technology-use activities (5 years · capped)
Activities that use technology meaningfully but don't develop it: automation-driven manufacturing, cold-chain logistics with IoT, certain digital services. Five years of zero Corporate Income Tax, capped at investment.
Group A4 — Lower-priority promoted activities (3 years · capped)
The shortest holiday in the A-tier. Standard manufacturing in non-priority categories, lower-tech services. Three years at 0%, capped at investment. Often the entry point for traditional manufacturing operations setting up a Thai entity.
Group B — Supporting promoted activities (no holiday · base rate)
Group B gets no Corporate Income Tax exemption — pays the standard 20%. But it still gets:
- Import-duty exemption on machinery
- Import-duty exemption on raw materials used in export production
- Land-ownership permission for promoted activity (a Foreign Business Act exemption)
- Streamlined foreign-worker visa & work-permit processing
- Free repatriation of foreign currency
For traditional manufacturing operations that need to import machinery and bring in foreign engineers, even Group B can be worth applying for — the non-tax benefits alone often justify the application cost.
Non-tax benefits everyone gets
Independent of the tax holiday tier, BOI promotion unlocks four non-tax benefits available to every promoted entity — A1+ through B:
- Land ownership for promoted activity — including by foreign-majority entities (a Foreign Business Act exemption that normally takes a Treaty of Amity route or 51% Thai shareholding).
- Bring in skilled foreign workers and experts on streamlined visa + work permit, including dependents. Avoids the 4:1 Thai-to-foreign hiring ratio for promoted roles.
- Investment-study permission for site visits, feasibility, and pre-launch presence in Thailand.
- Free remittance of foreign currency abroad — repatriate profits, dividends, and capital without Bank of Thailand approval.
Merit add-ons — stack on top of the base holiday
A1–A4 qualifying large projects under BOI Announcement No. 3/2569 (dated 15 January 2026) can layer extra incentives on top of the base holiday:
- 50% Corporate Income Tax reduction for 5 years after the holiday ends (so an A1 effectively pays 10% for years 9–13).
- Merit measures for R&D, HR development, skill upgrade — typically adds 1–2 yrs of holiday + extra exemption ceiling.
- EEC zone, industrial-zone location, and decentralization zones each layer extra benefits depending on activity.
Sources: Thailand BOI Investment Promotion Guide 2025; BOI Announcement No. 3/2569 dated 15 January 2026; BOI Quick Guide 2026; PwC Thailand Tax Incentives summary; Pertama Partners updated 9 February 2026. Current as of June 2026 — confirm latest with motherducker.tech consultancy before relying on these terms for commercial decisions.