Thailand financial year: choosing a company accounting period

The Revenue Code states that the corporate income tax accounting period is generally 12 months. It does not require every company to close on 31 December. A company may use another year-end when that period is properly established and used consistently.

That distinction matters for foreign-owned subsidiaries. A 31 March, 30 June or 30 September close may make group consolidation easier, but the local period still drives Thai annual tax and accounting work. Check it against the Thailand tax calendar rather than copying a parent-company calendar.

• Calendar year and accounting year are not automatically the same.
• Monthly VAT, withholding and payroll cycles continue within the chosen year.
• The closing date should match records, systems and filed returns.

For a newly incorporated company, the first accounting period can run from the incorporation date to any selected closing date, so it may be shorter than 12 months. The following period should then return to a 12-month cycle. A short first period is not an extra grace period; it brings the first close, accounts and annual tax work closer.

Compare at least two candidate year-ends. Consider the parent reporting date, revenue seasonality, inventory count, availability of directors and auditors, and whether the first period would be too short to establish reliable processes. The accounting and bookkeeping service should configure the chart of accounts, opening records and close calendar to the selected dates.

For an ordinary 12-month accounting period, the Revenue Department describes PND.51 as the half-year corporate income tax return due within two months after the first six months. PND.50 is the annual return due within 150 days after the accounting period closes. Use the current form and electronic instructions for the relevant year.

Revenue Code section 67 Bis says the half-year rule does not apply where the first or final accounting period is shorter than 12 months. Do not generalize that exception to every transition without checking the approved facts. Put the resulting dates into the tax compliance workflow and document why PND.51 is or is not expected.

Once a company has an established closing date, management should not shorten or extend the ledger year by preference alone. Revenue Code section 65 requires the Director-General's approval to change the last day of an accounting period. The DBD e-Permit system also lists permission to change an accounting year, and its manual describes supporting steps and evidence.

Plan the Revenue Department and DBD sequence together. The DBD manual indicates that an ordinary change application should be made no later than the requested new closing date and refers to Revenue Department permission evidence. If the articles specify the existing year-end, align the corporate documents first. Verify current requirements in e-Permit for the exact entity and change before relying on the new date.

A useful closing date puts the annual close at a point when finance staff, inventory records, directors and external reviewers can produce evidence. It may also reduce differences between local and group reporting. A poor date can create two close exercises, rushed estimates and avoidable audit questions.

The choice does not move monthly VAT, withholding tax or payroll duties into the annual cycle. Keep those controls running through the monthly tax filing checklist and use the year-end to organize the final reconciliation, not to postpone it.

For a first short period or an approved change, retain the incorporation or approval records, period decision, system configuration, opening and closing trial balances, tax-calendar assessment, filed returns and accepted receipts. Record which reporting package covers each date so no month falls between two periods.

Before the first annual close, reconcile the approved period across the ledger, PND.50 draft, financial statements and DBD data. The audit and annual compliance service can coordinate the close, but management should retain the evidence and approvals in company-controlled storage.

The most efficient review starts with the incorporation date, current year-end, prior financial statements and tax returns, articles, intended new date and reason for the change. Add the parent reporting calendar if group alignment is the objective.

Contact our accounting team before changing ledger settings or publishing a new deadline calendar. We can separate the period decision, approval evidence, tax dates and annual-close work into a controlled implementation plan.