BOI Compliance: What Promoted Companies Must Keep Doing (2026 Guide).

What BOI compliance means once you hold the certificate

BOI compliance is everything a promoted company must keep doing after the certificate arrives: meeting the conditions written into it, reporting progress on a fixed schedule, getting the project to full operation on time, and claiming the tax exemption through a formal, audited application. The promotion decision is a beginning. The benefits stay alive only while the obligations are met.

If you are still deciding whether to apply, or you are mid-application, that process has its own guide: applying for BOI promotion. This one assumes the certificate is already on your desk.

Think of the work in two tracks. Track one is BOI-specific: certificate conditions, e-Monitoring reports and the exemption application. Track two is the ordinary compliance every Thai company carries anyway: bookkeeping, audit and tax filings. A promoted company runs both at once.

The conditions written into your promotion certificate

Every incentive you received is granted as specified in the promotion certificate, and the certificate carries conditions. Investment amounts, the scope of the promoted activity, timelines and any project-specific terms the Board attached all bind the company for as long as it wants the benefits.

The BOI does not grant and forget. Its published functions include supervising project conditions, such as operation start-up, and following up on promoted projects through the e-Monitoring system, according to the BOI's investment promotion guide. Reading the certificate line by line, and diarising every date in it, is the first piece of real compliance work.

Quarterly progress reports through e-Monitoring

Until the project has been submitted for operation start-up, the company reports quarterly. Progress reports on the investment promotion certificate go through the e-Monitoring system within 30 calendar days of the end of each quarter, with the quarters closing in March, June, September and December.

Thirty days is a short window when the figures have to come out of live accounting records. Companies that keep their books current file these reports as routine; companies that reconstruct each quarter after the fact tend to miss the window or file thin numbers. This is one of the quieter arguments for disciplined monthly closing.

The annual performance report every July

Every July, the promoted company reports project progress and performance through the same e-Monitoring system. Where the quarterly reports track whether the project is being built, the July report looks at how the promoted project is actually performing.

Treat it as a fixed annual event alongside the statutory calendar, and prepare it from the same closed books that feed the audit and the tax return. Inconsistent numbers across those three documents invite questions from every direction.

The 36-month operation start-up deadline

A promoted company must request approval of full operation start-up within 36 months of the date the promotion certificate was issued. This is the hard outer deadline for turning a promoted project on paper into a running operation.

The request is not a formality. It is the point where the BOI checks that the project matches what was promised before the incentives settle in for the long run. Companies that see the date approaching with machinery still in transit should raise it with their advisers early. Options narrow as the deadline gets closer.

Keeping promoted and non-promoted income apart

The corporate income tax exemption covers net profit and dividends derived from the promoted activity. That phrase does the heavy lifting: income from anything outside the promoted activity is taxed normally, so a company earning both kinds of income has to be able to show which profit is which.

In practice, accountants make this provable by separating the books: revenue, direct costs and a defensible allocation of shared overheads, split between promoted and non-promoted operations in the chart of accounts. The BOI's published wording defines what the exemption attaches to rather than prescribing a bookkeeping method, so the structure of the split is something your accountant designs and your auditor tests. Set it up when the certificate arrives. Untangling a year of mixed records at filing time is slower and shakier than splitting them from the start, which is exactly the kind of structure a BOI accounting engagement exists to build.

Applying the corporate income tax exemption through e-Tax

Using the exemption is an application, not an assumption. The company prepares the supporting materials, has the application considered by a certified auditor, fills the auditor's opinions into the system, attaches the report of those opinions and submits the application through the e-Tax system to the BOI.

The auditor's opinion is the load-bearing part. It is what connects the exempt profit the company claims to books an independent professional has examined, and the auditors who sign are CPAs licensed under the Accounting Professions Act and regulated by the Federation of Accounting Professions. Which incentives your certificate actually carries, and how far each one reaches, is its own subject: the BOI tax incentives page covers that layer.

Normal Thai compliance does not pause

Promotion changes how much tax you pay, and it changes nothing about what you file. The annual corporate income tax return (CIT 50) is due within 150 days of the closing date of the accounting period, and a half-year return (CIT 51) with half the estimated tax falls two months after the first six months, per the Revenue Department. A promoted company files both even in years when the exemption reduces the tax to zero, and corporate tax filing for a BOI company leans on the same promoted-income split described above.

The financial statements chain runs in parallel. A limited company presents auditor-examined statements to its annual general meeting within four months of closing and files them with the registrar within one month of approval, per the DBD's filing manual. The statutory audit that produces those statements is also where the promoted versus non-promoted split gets tested by someone outside the company.

What happens when conditions slip

Benefits granted under a promotion certificate can be lost. The BOI's published functions include cancellation or partial withdrawal of rights and benefits, sitting alongside its supervision of project conditions. The guide's wording establishes that the power exists without spelling out the mechanics of each case, so the honest position is this: a missed condition puts the incentives at risk, and how a specific breach plays out depends on the condition, the project and the circumstances.

What that means practically: do not wait for the BOI to notice. If a reporting deadline was missed, a condition looks unachievable, or the 36-month date is in doubt, a firm that handles BOI matters can assess the exposure and approach the BOI with a plan rather than an apology.

The BOI compliance calendar at a glance

One page of dates captures most of the rhythm. Before operation start-up, the recurring deadlines for a promoted company on a calendar-year accounting period look like this:

• Within 30 days of each quarter end (March, June, September, December): quarterly progress report through e-Monitoring.
• Every July: annual project progress and performance report through e-Monitoring.
• Within 36 months of certificate issuance: request approval of full operation start-up. Once, and unmovable without engaging the BOI.
• Within 150 days of the accounting year's close: annual corporate income tax return (CIT 50), with the audited statements chain running on its own four-month and one-month deadlines.
• Two months after the first half-year: CIT 51 with half the estimated tax.

A company with a non-calendar accounting period shifts the tax dates accordingly; the e-Monitoring quarters stay fixed. Whoever keeps this calendar should own both tracks, because the same closed books feed every line on it.

Who does the BOI compliance work

Most promoted companies split it. Internal staff keep the day-to-day records; an external accountant maintains the promoted-income separation, prepares the e-Monitoring reports from the books and manages the exemption application with the auditor; the auditor, drawn from the audit firms in Thailand licensed for statutory work, examines the statements and signs the opinions the application needs. Smaller promoted companies often hand the whole accounting track to one outsourced team, and general accounting firms in Thailand that work with promoted clients build the BOI calendar into the standard monthly cycle.

There are no published official fees for this ongoing work to quote. Scope drives cost: the number of promoted projects, whether non-promoted income exists, and how clean the underlying records are. A firm quotes after seeing those three things.

This guide is general information about BOI compliance obligations in Thailand, based on the BOI's and the Revenue Department's published materials. It is not accounting, tax, or legal advice, and certificate conditions differ project by project. For decisions about your own promotion, speak with a qualified accountant, auditor, or BOI specialist.