Thailand Accounting Compliance Calendar: Every Monthly and Annual Filing

Running a company in Thailand means keeping several compliance clocks moving at the same time. Payroll withholding tax, VAT and Social Security can be due every month, while corporate income tax, audited financial statements and Department of Business Development filings follow separate half-year and annual deadlines.

For foreign founders, the challenge is often not calculating the tax. It is remembering which form goes where and when.

This guide explains the main Thailand tax filing deadline 2026 requirements for a typical Thai limited company. Companies with a financial year other than 1 January to 31 December should calculate PND.50, PND.51 and annual financial statement deadlines from their own accounting period.

Key takeaways

Thai companies can face monthly PND.1 withholding tax, PP.30 VAT and Social Security filings, each with its own deadline.

For a calendar-year company, PND.51 is due on 31 August 2026 or 8 September online, while the 2026 PND.50 deadline moved to 2 June, or 8 June for online filing.

Thai limited companies must have annual financial statements audited, approved by shareholders within four months after year-end and filed with the DBD within one month after approval.

Monthly cycle: PND.1, PP.30 and SSO

The easiest way to manage a Thailand tax calendar 2026 is to think of compliance as a repeating monthly cycle.

For many operating companies, three deadlines matter most.

Filing

What it covers

Normal deadline

PND.1

Employee salary withholding tax

Statutory monthly deadline around the 7th; Revenue Department online calendar generally allows e-filing to the 15th

PP.30

VAT return

15th of following month; generally 23rd for online filing

SSO Form 1-10

Employer and employee Social Security contributions

15th of following month

The Revenue Department's 2026 calendar shows monthly withholding filings such as PND.1, PND.3 and PND.53 normally due on the 7th and online submissions generally due on the 15th. PP.30 VAT returns are normally due on the 15th, with electronic filing shown on the 23rd.

There is an additional point employers should know about PND.1. The Revenue Department announced that employer filings of PND.1 and related annual forms moved to electronic channels from 2024. Businesses should therefore follow the current electronic filing process and the Revenue Department's published online deadlines.

PND.1: salary withholding tax

PND.1 reports personal income tax withheld from employee salaries.

This filing should be connected directly to payroll. Once salaries are calculated, your accounting or payroll team should determine the withholding tax for each employee, record the liability and submit the corresponding return.

Other withholding tax forms may also appear in the monthly cycle. For example, companies making certain payments to individuals or corporate suppliers may need PND.3 or PND.53.

PP.30: monthly VAT

VAT-registered businesses file PP.30 every tax month.

The Revenue Code requires a VAT registrant to submit its monthly return within the first 15 days of the following month. The Revenue Department's 2026 calendar generally provides an online deadline on the 23rd.

This means VAT should not be treated as a year-end accounting exercise. Input VAT documents, output VAT invoices and supporting records should be reconciled every month.

Social Security

Employers also have a separate Social Security cycle.

The Social Security Office instructs employers to submit Form SSO 1-10 and contributions by the 15th of the month following the payroll month. If the 15th falls on an official holiday, payment can be made on the next working day.

Because Revenue Department and Social Security filings run through different systems, businesses should not assume completing payroll automatically completes every government filing.

Half-year PND.51

PND.51 is the half-year corporate income tax filing.

Under the Revenue Code, companies generally estimate annual net profit and pay half of the estimated annual corporate income tax within two months after the end of the first six months of the accounting period. The amount paid is credited against the final annual corporate income tax liability.

For a company with a 1 January to 31 December accounting year, the official Thailand tax filing deadline 2026 is:

PND.51 deserves more attention than many founders give it. It is not simply an administrative form. Your accountant needs enough current bookkeeping information to make a reasonable estimate of the company's annual result.

Waiting until August to reconcile six months of transactions can make that estimate much harder.

Annual PND.50 and financial statements

PND.50 is the final annual corporate income tax return.

The Revenue Department requires companies and juristic partnerships to file the annual corporate income tax return within 150 days after the end of their accounting period.

For businesses whose accounting period ended on 31 December 2025, the normal 150-day deadline fell on 30 May 2026. Because that date fell during the holiday period, the Revenue Department's official calendar moved the filing deadline to 2 June 2026. Online filing was available through 8 June 2026.

This is a good example of why companies should not simply copy last year's dates into a spreadsheet. Weekends and official holidays can change the actual filing date.

PND.50 should also reconcile with your audited accounts, withholding tax credits and the PND.51 payment already made during the year.

Do not forget the DBD filing

Tax filing and financial statement filing are separate obligations.

For Thai limited companies, audited financial statements must be presented for shareholder approval within four months after the end of the accounting year. After approval, the company must submit the financial statements and auditor's report electronically to the Department of Business Development within one month after the shareholder meeting.

For a company with a 31 December year-end, this normally means planning the AGM no later than the end of April and preparing the DBD filing immediately afterwards.

Audit requirement: all Thai limited companies

A common misunderstanding among small businesses is that an audit is only required once the company becomes large.

That is not the rule for a Thai limited company.

DBD guidance states that the company's annual financial statements must be examined and an opinion issued by an authorised auditor. The audited statements are then submitted to shareholders for approval.

This means even a small Thai limited company should plan its year-end audit well before the filing deadline.

The practical sequence should look like this:

Close bookkeeping → reconcile tax accounts → prepare financial statements → auditor review → shareholder approval → DBD filing → complete annual tax reconciliation.

Leaving bookkeeping unfinished until the audit starts usually creates unnecessary pressure around the annual deadlines.

Businesses that prefer to outsource this cycle can use Settlr's accounting and tax services for monthly bookkeeping, tax filings and year-end compliance.

Penalty table

Missing a deadline can create several different costs. A late filing fine and a surcharge on unpaid tax can apply separately.

Compliance problem

Potential consequence

Late PND.50 filing

Fine of up to THB 2,000

Unpaid or late tax

Generally 1.5% surcharge per month or part of a month

PND.51 profit underestimated by more than 25% without reasonable cause

20% surcharge under Section 67 Ter

Late VAT payment

1.5% surcharge per month or part of a month, subject to the statutory cap

Late Social Security contribution

2% additional charge per month

Failure to submit approved financial statements to DBD within the required period

Civil fine of up to THB 20,000 for the company and up to THB 20,000 for the responsible managing director

The Revenue Department confirms that late PND.50 filing can result in a fine of up to THB 2,000. Tax not paid on time can generally attract a 1.5% monthly surcharge or part thereof.

For PND.51, Section 67 Ter provides for a 20% surcharge where estimated net profit is understated by more than 25% without reasonable cause.

For Social Security, SSO instructions state that late contributions attract an additional 2% per month, beginning after the payment deadline.

DBD guidance states that failure to submit approved financial statements through DBD e-Filing within the required one-month period can result in a civil fine of up to THB 20,000 for the company and THB 20,000 for the managing director.

The exact penalty depends on the type of violation and circumstances, so late filings should be corrected promptly rather than left until the next reporting period.

Calendar download

The simplest compliance system is one where deadlines appear automatically before they become urgent.

Instead of maintaining separate reminders for PND.1, PP.30, Social Security, PND.51, PND.50, the AGM and DBD filing, add them to one operating calendar.

See the full Thailand Tax Calendar 2026 for the complete filing schedule.

For companies with non-calendar financial years, your annual PND.50, PND.51, audit and DBD dates should be adjusted to your actual accounting period.

Download the ICS calendar and add the main Thailand accounting deadlines directly to your business calendar so your finance team has reminders before each filing date.

FAQs

What is the main Thailand tax filing deadline 2026 for monthly taxes?

There is no single deadline. Withholding tax forms generally follow a deadline around the 7th of the following month, with Revenue Department e-filing normally shown around the 15th. PP.30 VAT is normally due on the 15th or around the 23rd electronically.

When is PND.51 due in 2026?

For companies using a January to December accounting year, PND.51 is due 31 August 2026, with the Revenue Department's electronic filing date shown as 8 September 2026.

When is PND.50 due in 2026?

PND.50 is normally due within 150 days after the accounting year ends. For companies whose financial year ended on 31 December 2025, the official 2026 deadline moved to 2 June 2026, with online filing available through 8 June 2026.

Does every Thai limited company need an annual audit?

Yes. DBD guidance requires Thai limited company financial statements to be audited by an authorised auditor before being presented to shareholders for approval.

When do financial statements need to be filed with the DBD?

The audited statements must be approved at a shareholder meeting within four months after year-end and submitted to the DBD within one month after approval.

How can a company avoid missing Thailand tax deadlines?

Keep bookkeeping current every month rather than rebuilding the accounts before PND.51 or PND.50. Assign ownership for payroll, VAT, withholding tax, SSO and annual filings and keep all deadlines in one shared calendar.

Never miss another filing deadline. Download the ICS calendar and put Thailand's key tax, accounting and compliance dates directly into your calendar.