Year‑end payroll checklist for Thai businesses.

As the calendar year closes, finance and HR leaders in Thailand face a concentrated period of payroll work. This is when year‑to‑date data must be reconciled, statutory filings completed, and employees given the documents they need for their personal tax returns. Getting it right protects the business from penalties, reassures staff, and sets a clean foundation for the new payroll year.

This guide distils the essential year‑end tasks in Thailand into a clear, practical checklist explaining what must be filed, when it is due and how to avoid the pitfalls that commonly lead to errors and fines.

Why year‑end payroll compliance matters in Thailand

Year‑end is the moment when small monthly discrepancies turn into costly issues. Misstated taxable allowances, omitted overtime or miscoded benefits can distort the annual withholding position and force corrective filings.

Verifying that year-to-date (YTD) pay and tax match the monthly submissions helps prevent discrepancies in the P.N.D.1 Kor reconciliation. The Revenue Department sets strict deadlines, 28 February for paper filings and 8 March for electronic submissions, leaving minimal time to correct any errors discovered late.

Legal obligations under Thai labour and tax rules

Employers are required to withhold personal income tax and submit monthly (P.N.D.1) and annual (P.N.D.1 Kor) returns. Starting 1 January 2025, all withholding returns must be filed electronically.

At the same time, employers must calculate and remit monthly social security contributions and complete the annual Workmen’s Compensation Fund (WCF) steps. These obligations are governed by the Revenue Code and the Social Security Act, with the social security e‑payment deadline extended to the 22nd of each month from 2025 through 2029.

Risks of non‑compliance

Late or incorrect filings can lead to surcharges, penalties or audits. Incomplete employee certificates delay personal filings for staff (P.N.D.90/91 are due by 31 March on paper or 8 April electronically), eroding confidence and increasing HR workload.

Weak controls also raise exposure under Thailand’s Personal Data Protection Act (PDPA) because payroll records contain sensitive personal data that must be processed lawfully and securely.

Year‑end payroll checklist for Thai businesses

The following is a comprehensive checklist to guide Thai businesses through year‑end payroll reviews and ensure accurate reporting and compliance.

Review employee records and contracts

Start by performing a thorough data integrity check. Verify that employee names, tax identification numbers, bank details, start and end dates, salary bands, job titles and work locations match the information in contracts and human resources information system (HRIS) records.

Ensure that promotions, transfers, secondments and new hires throughout the year are accurately reflected in the payroll master and monthly filings. This step is particularly important for employees on cross‑provincial assignments, where minimum wage rates and allowances may vary following the July 2025 update.

Additionally, confirm that all taxable and non‑taxable benefits, such as meal or transport allowances, in‑kind benefits, and reimbursements, are correctly classified. Accurate classification ensures that year‑end totals align with the Revenue Department’s treatment in P.N.D.1 and are correctly reflected on each employee’s 50 tawi certificate.

Verify salary, overtime and allowances

Reconcile the total gross pay in payroll reports with the general ledger and with the sum of monthly P.N.D.1 filings. Check overtime calculations against the Labour Protection Act thresholds and rates, and verify that allowance policies have been applied consistently. Where variable pay is used (commissions or shift premiums), ensure it is included in taxable income in the correct pay period so December true‑ups are accurate and minimal.

Calculate year‑end bonuses and benefits

Thailand does not require a 13th‑month salary. However, many employers provide discretionary year‑end bonuses based on performance or company policy. If a bonus is contractually guaranteed, it should be calculated according to the employment agreement.

Regardless of the approach, the bonus must be included in taxable income in the month it is paid, with the appropriate tax withheld. Ensure the amount is accurately reflected on the annual P.N.D.1 Kor and in the employee’s withholding certificate.

Ensure proper tax withholdings and social security contributions

At year‑end, conduct a withholding reconciliation by recalculating each employee’s full-year assessable employment income and comparing it with the cumulative tax already withheld. Any under‑ or over‑withholding should be adjusted in the December payroll where possible. From January 2025 onward, withholding returns must be filed exclusively through the Revenue Department’s e‑filing system.

For social security, ensure that monthly contributions, generally 5% each for the employer and employee, capped at THB 750 per party, are calculated on the correct wage base and that recorded postings match actual payments. The standard payment deadline is the 15th of the following month. For electronic payments, the Social Security Office (SSO) allows an extended deadline of the 22nd for salaries paid from January 2025 through December 2029.

Prepare statutory filings and employee tax documents

Ensure all required tax and social security filings are completed accurately and on time for year-end compliance:

• Withholding tax (Revenue Department):
  • Continue monthly filings on P.N.D.1, observing the 7th (paper) or 15th (e‑file) deadlines. From 1 January 2025, withholding tax returns must be submitted via e‑filing.
  • File the annual P.N.D.1 Kor (the year‑end summary of employment income subject to withholding) by 28 February on paper or by 8 March electronically.
• Employee tax certificates (50 tawi under section 50 bis): Issue annual withholding certificates to current employees by 15 February; for employees who left during the year, issue within one month of departure. Employees attach these to their personal tax returns (P.N.D.90/91), due 31 March on paper or 8 April electronically.
• SSO: Continue monthly submissions and payments and prepare for the WCF cycle.

Audit payroll records for accuracy and compliance

Reconcile payroll registers, P.N.D.1 totals, P.N.D.1 Kor draft data and social security submissions with the accounting ledger, ensuring all figures align. Maintain clear audit trails for any adjustments, particularly those made in December.

Since payroll contains personal data, confirm that PDPA‑compliant controls are in place, restricting access, retaining only necessary information and documenting the lawful basis for all data processing.

Plan for the Workmen’s Compensation Fund (WCF)

Thailand’s WCF is an annual, employer‑funded scheme administered by the SSO. Year‑end and early‑year actions typically follow this cadence:

• Kor Tor 26 Kor: SSO issues an estimated contribution for the new year based on prior wages; pay by end‑January
• Kor Tor 20 Kor: Report actual total wages for the prior year by end‑February
• Kor Tor 25 Kor: If the reconciliation indicates an additional assessment, pay by end‑March

Plan for the new payroll year

Update payroll software and tables

Load the current provincial minimum wage schedule effective 1 July 2025 and verify that any location‑based pay rules are mapped correctly. If workforce spans provinces or specific business categories, confirm the correct daily wage applies (for example, Bangkok at THB 400 per day, and special sector rules for hotels of certain types).

Monitor policy changes

The government has postponed the Employee Welfare Fund (EWF) contributions to 1 October 2026 (previously 1 October 2025). Track official notices and be ready to update systems and employee communications when the start date approaches.

Communicate with employees

Explain when they will receive their 50 tawi, how to check details and where to find support for P.N.D.90/91 filing, particularly important for new hires and expatriates. Remind them of the 31 March paper and 8 April e‑filing deadlines.

How to manage year-end payroll effectively

Set internal deadlines ahead of statutory cut‑offs

Work backwards from the 28 February/8 March P.N.D.1 Kor deadline and the 15 February 50 tawi issuance date. Lock an internal cut‑off for variable pay in December, and set a firm window for final employee data changes. This allows time for quality checks and re‑runs before submissions.

Maintain clear documentation

Keep a year‑end pack that includes

• YTD payroll summaries
• Reconciliation workpapers
• Copies of submitted P.N.D.1 and the final P.N.D.1 Kor
• 50 tawi samples
• SSO payment confirmations
• WCF forms (Kor Tor 26 Kor, 20 Kor, 25 Kor)

A complete pack reduces audit stress and accelerates handovers if team members change.

Use technology wisely (or outsource)

If in‑house capability is limited, consider using a payroll platform aligned to Thai e‑filing standards or outsource to a specialist provider. From 2025, the Revenue Department’s mandatory e‑filing for withholding returns makes manual workarounds riskier.

Professional support ensures filings land on time and in the correct format, while also scaling to handle WCF, social security and personal data protection hygiene.

Build in controls for common errors

Typical mistakes include misclassifying allowances, omitting income from final‑pay runs and missing WCF deadlines in January–March. Counter these with standard checklists, automated variance checks and a single owner for WCF steps who tracks the three separate forms and their timing.

Conclusion

Year‑end payroll in Thailand is a critical period that requires careful coordination across finance, HR, and compliance functions. By systematically reviewing employee records, verifying salaries, allowances, and bonuses, reconciling tax and social security contributions, and preparing all statutory filings, employers can reduce the risk of errors, penalties, and employee dissatisfaction. Maintaining clear documentation, implementing PDPA‑compliant controls and planning for the Workmen’s Compensation Fund further strengthen compliance and audit readiness.

Looking ahead, updating payroll systems, monitoring regulatory changes and communicating clearly with employees set the stage for a smooth transition into the new payroll year. Following this checklist ensures that businesses not only meet their legal obligations but also foster trust and confidence among their workforce.

How Acclime can help with payroll services

Acclime provides end‑to‑end payroll outsourcing in Thailand, combining compliant setup with accurate monthly processing and seamless statutory reporting. The team handles employer registrations with the Revenue Department and SSO, configures gross‑to‑net calculations to Thai rules, issues secure payslips, and submits P.N.D.1 and P.N.D.1 Kor on time via e‑filing. Support also covers WCF steps (Kor Tor 26 Kor, 20 Kor and 25 Kor), year‑end reconciliations, and employee certificate issuance, with coordinated assistance for expatriate populations. This integrated service reduces administrative effort and compliance risk, freeing HR and finance teams to focus on operations and growth. Contact us today to learn more about Acclime’s Thailand payroll services.