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PND.1 Kor is Thailand’s annual summary of withholding tax on employment income. Employers file it once a year with the Revenue Department, listing every employee’s total income and tax withheld. For 2026 income, paper filing is due by 28 February 2027 and online filing by around 8 March 2027. Employers must also issue each employee a 50 Tawi withholding certificate by 15 February.
Year-end is the heaviest period for payroll. On top of December salaries there are bonuses, joiners and leavers, and tax documents that all have to match. One wrong figure affects both PND.1 Kor and employees’ 50 Tawi certificates, and fixing it later clashes with employees’ own tax filing. This guide explains PND.1 Kor and gives your HR and finance teams a shared year-end checklist.
💡 What is PND.1 Kor?
PND.1 Kor (ภ.ง.ด.1ก) is the annual withholding tax summary under the Thai Revenue Code. Employers use it to report each employee’s assessable income and tax withheld for the whole tax year. It is filed once a year and involves no additional tax payment.
PND.1 Kor vs monthly PND.1
| PND.1 | PND.1 Kor | |
|---|---|---|
| Frequency | Every month with payments | Once a year |
| Purpose | Remit tax withheld that month | Summarise the full year |
| Employees listed | Those with tax withheld | Every employee paid during the year, including those with no tax withheld |
| Paper deadline | Within 7 days after month end | By 28 February of the following year |
| Online deadline | Within 15 days after month end | Extended by about 8 days |
Key facts:
- Monthly PND.1 is due within 7 days after month end, extended to 15 days for e-filing (Revenue Department).
- PND.1 Kor is due by 28 February on paper or around 8 March online, and must list every employee, even those with no tax withheld (Revenue Department).
- The social security wage ceiling rose from THB 15,000 to THB 17,500 on 1 January 2026, raising the maximum monthly contribution from THB 750 to THB 875 (Social Security Office).
For monthly basics, see our guide on calculating withholding tax (PND.1).
Year-end timeline: December 2026 to March 2027
| When | Task |
|---|---|
| Early Dec 2026 | Ask employees to update allowance forms (L.Y.01) |
| Before December payroll | True up December tax and calculate bonus tax |
| By 7 Jan 2027 (online 15 Jan) | File PND.1 for December 2026 |
| By 15 Feb 2027 | Issue 50 Tawi certificates to all employees |
| By 28 Feb 2027 (online ~8 Mar) | File PND.1 Kor |
7-point year-end payroll checklist
- Joiners and leavers: include everyone paid in 2026, including those who have left. Leavers should receive a 50 Tawi within one month of leaving.
- Personal data: 13-digit tax IDs, names and addresses must match ID cards, or employees’ own filings will fail.
- Allowances (L.Y.01): update deductions employees have declared, such as spouse, children and life insurance.
- Bonuses: calculate bonus tax using the full-year comparison method below.
- New social security ceiling: 2026 is the first year of the THB 17,500 ceiling. Check every month used it correctly.
- Provident fund: confirm each employee’s full-year contributions, which can be deductible.
- Reconcile 12 months: total income and tax from all 12 PND.1 filings must equal PND.1 Kor and each 50 Tawi.
Point 7 usually takes the longest when data sits in several files. A payroll automation system that keeps every pay run in one place makes reconciliation much faster.
How to withhold tax on bonuses (worked example)
Calculate full-year tax including the bonus, then subtract full-year tax without it. The difference is withheld in the bonus pay period.
Example: monthly salary THB 40,000, bonus THB 80,000, personal allowance THB 60,000, social security THB 10,500 (875 × 12).
| Without bonus | With bonus | |
|---|---|---|
| Annual income | 480,000 | 560,000 |
| Expense deduction (50%, max 100,000) | 100,000 | 100,000 |
| Personal allowance | 60,000 | 60,000 |
| Social security | 10,500 | 10,500 |
| Net taxable income | 309,500 | 389,500 |
| Annual tax | 8,450 | 16,450 |
Tax on the bonus = 16,450 − 8,450 = THB 8,000. Monthly salary tax stays at about THB 704. (Progressive rates: 5% on THB 150,001–300,000 and 10% on THB 300,001–500,000.) Bonuses are generally not treated as wages for social security, so no extra contribution is deducted.
Issuing 50 Tawi and filing PND.1 Kor
50 Tawi: issue to every employee paid during the year by 15 February. Income, tax withheld, and social security and provident fund amounts must match PND.1 Kor. PDF delivery through online channels saves a lot of distribution work.
PND.1 Kor: prepare every employee’s tax ID, annual income and annual tax withheld, then file through the Revenue Department’s e-Filing system, which supports file import. Organisations with hundreds of employees should import rather than key in each person.
Common year-end mistakes
- Leavers missing from PND.1 Kor
- 50 Tawi figures not matching PND.1 Kor after an edit in only one file
- Bonus tax withheld at a flat rate, distorting full-year tax
- The old THB 15,000 social security ceiling still used in some months
- Allowance changes declared mid-year not updated
All of these come from data living in too many places. A payroll system that generates 50 Tawi and the PND.1 Kor file from the same employee and pay-run data removes re-keying and most of the risk. Overtime errors are another common cause of mismatches, so check OT calculations before closing the year.
PND.1 Kor is only as accurate as the 12 months of data behind it. Before closing 2026, check joiners and leavers, allowances, bonus tax and the new social security ceiling, then reconcile monthly PND.1 filings with PND.1 Kor and 50 Tawi. See how Pinno generates 50 Tawi and PND.1 Kor files automatically in Pinno Payroll Automation.
⚠️ Filing deadlines can change with Revenue Department announcements. Check the latest notice at rd.go.th before filing.
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Frequently Asked Questions (FAQ)
Q: When is PND.1 Kor due?
A: For 2026 income, paper filing is due by 28 February 2027. Online filing is extended by about 8 days, to around 8 March 2027. Check the Revenue Department’s notice for the year before filing.
Q: Do employees with no tax withheld appear on PND.1 Kor?
A: Yes. PND.1 Kor lists every employee who received income during the year, even if they were below the tax threshold. Monthly PND.1 lists only those with tax withheld.
Q: When must employers issue 50 Tawi certificates?
A: By 15 February of the following year for current employees, so they can file personal tax returns. Employees who left during the year should receive theirs within one month of leaving.
Q: Is social security deducted from bonuses?
A: Generally no, because bonuses are not treated as wages for social security. Bonuses are still taxable and must be included in annual income on PND.1 Kor and 50 Tawi.
Q: Can a PND.1 Kor filing be corrected?
A: Yes, by filing an additional return. It is easiest before employees file their own taxes, since corrected 50 Tawi certificates must also be reissued.
