The first question many business owners ask is "how many years of tax exemption does BOI give?" It is a fair question, but answering only that often leads to the wrong conclusion: some projects get 8 years of exemption and save almost nothing, while others get a shorter exemption but gain far more from machinery duty relief and easier visas for foreign staff.
To decide whether BOI is worth it, put "what you gain" and "what it costs" side by side in one table.
1. What you gain: four benefits you can quantify
| Benefit | How to calculate | Key variables |
|---|
| Corporate income tax exemption | Taxable profit during the exemption period × 20% (Thai CIT rate) | Years of exemption, exemption cap, whether you are actually profitable during the period |
| Import duty on machinery | Value of imported machinery × applicable duty rate | Where the machinery comes from; whether a free trade agreement rate already applies |
| Import duty on raw materials for export | Imported raw materials used in exported products × applicable duty rate | Export share; whether raw materials are imported |
| Dividends from exempt profits | Dividend tax on exempt profits distributed to shareholders is waived | Whether dividends are paid within the required period |
There is also a category that is hard to put a number on but is often decisive — non-tax privileges: eligibility for foreign ownership (through a Foreign Business Certificate, FBC), visa and work permit facilitation for foreign technicians and managers, and the right for a foreign-owned company to hold land for the project.
2. What it costs: three types of cost
| Cost | What it involves |
|---|
| Time | Eligibility assessment, application preparation, review and interview usually take months; incentives cannot be used before approval (see How long does BOI approval usually take?) |
| Conditions | Minimum investment, debt-to-equity ratio, start-up date, location and machinery conditions are written into the certificate, and changes need approval; larger projects must also obtain ISO or equivalent quality certification within a set period |
| Ongoing compliance | Separate accounting for BOI and non-BOI business, machinery and raw material list filings, raw material reconciliation, progress reports and annual exemption applications; poor compliance can lead to incentives being clawed back |
3. Worked example: a mid-sized manufacturing project
The figures below are assumptions to show the method; this is not a real project.
Project: manufacturing in a leased factory; investment excluding land and working capital THB 100 million
Imported machinery THB 40 million, assumed average duty 5%
60% of output exported; imported raw materials for exported products THB 30 million a year, assumed average duty 5%
Losses in years 1 and 2 after start-up; taxable profit of THB 20 million a year from year 3
Assumed 8-year CIT exemption, capped at 100% of the investment
| Benefit | Calculation | Amount (THB) |
|---|
| Corporate income tax (profitable in 6 of the 8 exempt years) | 20 million × 20% × 6 years | 24 million (below the 100 million cap) |
| Machinery duty | 40 million × 5% | 2 million |
| Raw material duty for exports (8 years) | 30 million × 5% × 8 years | 12 million |
| Total | | About 38 million |
On these numbers, BOI is "worth it". But change just one assumption and the answer can flip:
If the project makes no profit for the first 5 years: only 3 of the 8 exempt years are profitable, saving just THB 12 million in CIT. The exemption period starts from the first operating income, so loss years "use up" exemption years. BOI does allow losses incurred during the exemption period to be deducted for 5 years after it ends, which recovers some of this.
If all products are sold domestically: the THB 12 million of raw material duty savings disappears.
If machinery comes from a country that already has zero duty under a free trade agreement: the THB 2 million of machinery duty savings disappears too.
So in the same industry with the same investment, the value of BOI can differ several times over. Always run the numbers for your own project instead of borrowing someone else's conclusion.
4. Five situations where BOI is usually "not worth it"
Profits come late or margins stay thin: most of the exemption period falls in loss years, so the income tax benefit shrinks.
Almost everything is sold domestically and raw materials are bought locally: the duty benefits cannot be used.
Small investment with little machinery: the savings do not cover the application time and ongoing compliance effort.
The business is not BOI-promotable and is forced into a category: approval risk is high and the business scope is restricted after approval (see Can our project apply for BOI, and what are the main conditions?).
No internal capacity to maintain compliance: if machinery lists, raw material reconciliation and separate accounts are not kept properly, incentives may be clawed back later — worse than not applying.
Conversely, projects with large machinery investment, a high export share, a Chinese technical team that needs to stay in Thailand long term, or a business that needs foreign ownership eligibility usually find that BOI's overall value clearly exceeds its cost (see What tax and operational benefits can BOI provide?).
5. Suggested decision sequence
Check whether the business maps to a BOI-promotable activity and which incentive tier it can get.
Using your own investment, imported machinery, export share and profit forecast, calculate the benefits with the table above.
List the application time and the people and external services needed for ongoing compliance.
Compare the two; if the difference is small, let non-tax needs — foreign ownership, foreign staff, land — decide.
6. Basis and scope of service
Basis: Board of Investment (BOI) 2025 Investment Promotion Guide and project approval criteria (minimum investment, debt-to-equity ratio, CIT exemption periods and caps by category); BOI rules on import duty exemptions for machinery and raw materials for export and on carrying forward losses from the exemption period; the 20% corporate income tax rate under the Thai Revenue Code. Actual incentives follow current BOI announcements and your approved certificate. Z&X can help with eligibility assessment and benefit calculations; approval rests with the BOI, and no adviser should "guarantee approval".
Want to run the numbers for your own project? Book a BOI eligibility and category review →
Related services: BOI Investment Promotion Application | BOI End-to-End Compliance Services
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