PND 50 and PND 51: the two corporate tax filings Thai companies must connect

Revenue Code Section 67 Bis places the half-year return within two months after the first six months of an accounting period. Sections 68 and 69 place the annual return within 150 days after the period ends. A calendar-year company therefore usually works from 30 June for PND 51 and 31 December for PND 50, while a company with a different approved closing date follows its own cycle.

Do not build the calendar from habit or from another group company. Verify the registered period, short first period and any approved change first. The Thailand financial-year guide explains the period choices, while the monthly tax filing article keeps PND 51 and PND 50 separate from recurring VAT and withholding returns.

• Calendar-year example: the first six months end on 30 June, so the statutory PND 51 window ends two months later.
• The PND 50 statutory period is 150 days from the actual accounting year-end.
• Check the current Revenue Department calendar and e-filing rules before relying on a holiday or online extension.

For an ordinary company taxed on net profit, PND 51 generally starts with estimated annual revenue and expenses, produces estimated annual taxable profit, and charges tax on half of that estimate. The payment becomes a credit in the PND 50 calculation. The current form also contains different computation routes for certain regulated businesses, so the ordinary estimate method should not be applied blindly to every taxpayer.

A defensible forecast connects actual results for the first six months with signed contracts, recurring revenue, payroll, rent, depreciation, foreign-exchange assumptions, one-off transactions and tax adjustments expected in the second half. Use the same ledger mapping as the accounting and bookkeeping service so management reporting and the tax estimate can be compared line by line.

Section 67 Ter and the Revenue Department's PND 51 FAQ state that underestimating annual net profit by more than 25 percent without reasonable cause can create a surcharge of 20 percent on the relevant underpaid tax. The test concerns the estimated net profit compared with the final result, not whether the finance team honestly expected a quiet second half.

Keep the budget version, assumptions, board or management approval, signed sales pipeline, exceptional-event evidence and calculation memo used on the filing date. The Revenue Department identifies defined reasonable-cause situations, but they are not a substitute for contemporaneous support. If performance changes sharply, ask the tax compliance team whether an additional filing or another response is appropriate before year-end.

PND 50 does not simply copy profit before tax from the financial statements. Thai corporate income tax uses the accounting result as a starting point and applies Revenue Code rules to income, deductible expenses, depreciation, losses, exemptions and incentives. The current form then deducts eligible withholding tax and PND 51 credits to reach tax payable or overpaid.

Prepare a tax bridge that names every adjustment and links it to an account, document and legal basis. Common review areas include expenses without an identifiable recipient, private or non-business costs, capital items, provisions, depreciation differences, related-party charges and income recognized in the wrong period. Test these during an accounting health check, not only on the filing day.

The Revenue Code requires accounts supporting the annual return, and the PND 50 form identifies the auditor, accountant and core financial statements. Filing audited statements with the Department of Business Development is a separate corporate obligation even when electronic data is shared between agencies.

Reconcile revenue, profit before tax, retained earnings, tax expense, related-party balances and the accounting period across both submissions. A mismatch may be explainable, especially because taxable profit differs from accounting profit, but the explanation should already exist in the close file. The annual financial statements guide maps the DBD and shareholder timeline.

PND 51 tax paid and qualifying withholding tax can reduce the PND 50 balance, but only if the company can match each amount to the correct taxpayer, accounting period and official evidence. A spreadsheet total without receipts and certificates is not a reliable reconciliation.

Maintain a credit register throughout the year with payer, certificate number, income type, gross amount, tax withheld, filing period and ledger entry. Investigate duplicates and unmatched amounts before the audit closes. The withholding tax guide explains the evidence trail from payment to certificate.

The Revenue Department's PND 50 FAQ warns that an online return with tax due is not successfully completed if payment is not made within the required time. Save the submitted return, payment confirmation and official receipt, and verify their taxpayer number, period and amount rather than relying on a prepared-return screenshot.

Contact our Bangkok accounting team with the trial balance, accounting period, prior PND 50, current PND 51 forecast, withholding certificates and incentive details. We can build the deadline, forecast, tax bridge and credit checklist before the return reaches approval.