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Half-Year Corporate Income Tax Return — PND.51 ภ.ง.ด.51

Half-year estimated CIT — pay half of full-year projected tax. Late or under-estimated filing triggers surcharge.

Who

Active juristic persons (except first/last year of operations)

Service fee

Ask our team

Timeline

Depends on the issuing office

Authority

Revenue Department

Legal Basis

Revenue Code Sec. 67 bis

Eligibility

  • Juristic person with > 1 full accounting period

Required Documents

  • Mid-year management accounts
  • Annual profit projection

Procedure

  1. Project full-year profit
  2. Compute half-year tax
  3. File ภ.ง.ด.51 + pay

Fee Structure

If actual annual profit > 25% above projection, surcharge of 20% on under-paid tax under Sec. 67 ter.

Cross-Border / DTA Notes

Critical for BOI companies — surcharge erodes tax holiday benefit.

Related Services

ILC handles e-Filing, certified copies, certified translation and MFA legalisation, then checks whether the receiving authority requires embassy attestation. Thailand's Apostille Convention takes effect on 28 February 2027; until then the existing legalisation chain applies.

Post-Service Policy

If a document is rejected due to a defect in our translation or certification, our team coordinates corrections under our service policy and the terms of your quotation. This is not a guarantee of Revenue Department / MFA / embassy discretion.

Ask about fees — LINE @THAIL · Tel 092-0170000

Contact us
Accountant checking a Thai PND.51 form against supporting documents

What PND.51 is

The half-period corporate income tax return — an advance payment based on estimated full-year net profit, later credited against PND.50.

Deadline and exemptions

Due within 2 months after the first 6 months of the accounting period. Companies whose first period is shorter than 12 months, and other legally exempt cases, may not need to file.

Risk of under-estimating

If the estimate falls short of actual profit by more than 25% without reasonable cause, a surcharge may apply, so base estimates on real accounting data.

Frequently asked questions

Do listed companies calculate differently?

Certain types use actual reviewed half-year profit as the law prescribes.

Must I file with a half-year loss?

If not exempt, file even when no tax is payable.

Send your documents for our accounting team to review

Call 092-0170000 · LINE @THAIL · contact@thailaw-accounting.co.th

Fees: ask our team for a quote

Sources

Reviewed by the accounting team at Thai Law & Accounting Services · Last reviewed 4 Oct 2026 · General information, not tax or legal advice for your specific case

Go deeper on Tax document certification

These guides outline possible certification steps; confirm the receiving authority's current requirements before filing:

Not sure which route applies? Send us the scan — LINE @THAIL · 092-0170000 · contact@thailaw-accounting.co.th

Documents usually required

  • Freshly issued original Thai civil or corporate record from the issuing office
  • Complete English translation of every page, with the translator's statement of accuracy
  • Copy of the document holder's passport or Thai national ID card
  • Power of attorney with ID copies of both parties if someone else files on your behalf

Common reasons a bundle is rejected

  • Residency certificates are issued for a specific tax year and cannot be reused.
  • Treaty claims require the article to be cited correctly on the form.
  • Spell every name exactly as it appears in the passport, across every document in the same bundle.

Prefer not to handle the chain yourself? Send the scans and we run every step for you, from translation to the final endorsement.

How the process runs — Tax document certification

  1. Obtain a freshly issued original from the office that produced the record and check that every page is present.
  2. Prepare a complete translation with the translator's statement of accuracy attached.
  3. File for legalization at the Department of Consular Affairs, Ministry of Foreign Affairs, with the original and the translation together.
  4. Complete the next certification layer required by the destination country — Apostille, or legalization at that country's embassy in Thailand.
  5. Collect the finished bundle, scan a full copy for your records, then submit it in the format the receiving authority specifies.

Fees and processing times are set by each authority and vary by document and destination — confirm them with the responsible agency.

Handling it yourself vs letting ILC run it

AspectDoing it yourselfWith ILC
Working out which steps applyYou read each authority's rules yourself, and usually learn a step was missing only after the bundle is refused.Our advisers review the documents before work starts and sequence translation, notarisation, MFA, and embassy in one pass.
Time spent filingRepeat trips to each office, queueing and collecting in person.We file on your behalf; you send scans and receive the finished set by post or courier.
Risk that the translation is refusedAgency names, job titles, and the certification wording often do not match what the receiving office accepts.We use terminology and certificate formats the receiving authority has accepted before, with two-stage proof-reading.
If the bundle is rejectedYou diagnose the cause and refile yourself, losing a full cycle.We identify the cause, correct it, and refile without you starting over, with progress reported along the way.

What clients typically use this for

  • Tax residency certificates
  • Double-tax treaty claims
  • Overseas audit and reporting

An advisor, not only a document processor

Before any work starts, our team assesses how many certification layers your document actually needs, which authorities are involved, and the correct order for the office you will really file with. One step out of order usually means restarting the whole bundle. We work to recognise how each authority rejects files and prevent it up front.

  • The certification route is matched to the receiving authority before work begins.
  • Rejection risks are checked, from name spelling to document validity windows.
  • The filing sequence is planned around the deadline you actually have.

Consult us at LINE @THAIL · 092-0170000 · contact@thailaw-accounting.co.th

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