Payroll and social security in Thailand: an employer's guide for 2026

Your first hire in Thailand triggers an ongoing cycle of payroll and compliance obligations. Within 30 days of that first hire you must register as an employer with the Social Security Office (SSO). Every month after that you withhold personal income tax at progressive rates of 0% to 35% and remit it on form PND.1 (ภ.ง.ด.1) — which the Revenue Department requires employers to file electronically — by the 15th of the following month, and you pay social security contributions of 5% from the employee plus 5% from the company, capped at THB 875 each side, by the 15th.

Once a year the loop widens. The Workmen's Compensation Fund contribution falls due by 31 January. Employers with 10 or more staff file the annual employment-conditions disclosure — the Kor Ror 11 (คร.11) — within January. The PND.1 Kor (ภ.ง.ด.1ก) annual summary goes to the Revenue Department within February, and you must issue every employee a withholding-tax certificate under Section 50 bis of the Revenue Code — the 50 tawi (50 ทวิ) — by 15 February.

Each obligation is manageable in isolation; the risk is coordinating recurring deadlines across three authorities. Late payment of the main liabilities carries its own statutory charge — 1.5% per month for late PND.1 tax, 2% for social security contributions, and a separate monthly surcharge on unpaid Workmen's Compensation contributions — and the deadlines cluster in the first half of every month. This guide follows the cycle in the order employers encounter it: one-off registrations, monthly payroll, year-end filings and the additional steps for foreign staff.

What do you have to register when you hire your first employee?

Registration is a single event with a hard deadline. An employer with one or more employees must register with the Social Security Office within 30 days of the first hire, on employer registration form SSO 1-01 (สปส.1-01). One registration covers both funds the SSO administers — the Social Security Fund, on monthly contributions, and the Workmen's Compensation Fund, on an annual cycle — though a few business types are excluded from the Workmen's Compensation regime by law.

After registration, keep the SSO records current for each employee:

• New hires — form SSO 1-03 (สปส.1-03): each employee must be registered as an insured person within 30 days of their start date. The SSO's e-Service portal handles this online.
• Leavers — form SSO 6-09 (สปส.6-09): when someone stops working for you, notify the SSO by the 15th of the following month, stating the reason for departure.
• Why the deadline matters: intentionally failing to register is a criminal offence under the Social Security Act — up to six months' imprisonment or a fine of up to THB 20,000, or both.

There is no separate tax registration for payroll: PND.1 filings run under the company's existing taxpayer identification.

What does the monthly payroll cycle look like?

A well-run payroll month follows a fixed sequence: calculate, pay and file.

• Before payday — confirm inputs: salary changes, unpaid leave, overtime, commissions, and any joiners or leavers in the period.
• Payday — pay net, not gross: deduct withholding tax and the employee's 5% social security share, and give each employee a payroll statement — good practice at any headcount. Employers with 10 or more staff must also keep statutory wage-payment records under section 114 of the Labour Protection Act; bank-transfer evidence counts.
• By the 15th of the next month — PND.1: file the withholding-tax return electronically and remit the tax deducted — e-filing has been mandatory for PND.1 since 2024, and the deadline moves to the next working day when the 15th is a holiday.
• By the 15th of the next month — SPS 1-10 (สปส.1-10): file the social security return and pay the employee's 5% contribution and the employer's matching 5%. Employers filing and paying through the SSO's e-Payment channel get a further seven working days under an extension currently announced for wage months through December 2029.
• Rolling — joiners and leavers: register new staff within 30 days and report departures by the 15th of the following month, as above.
• Always — keep the records: under section 115 of the Labour Protection Act, employee registers and wage-payment records are kept for at least two years — longer while a labour complaint or case is pending. Payroll records that support the company's accounts fall under the Accounting Act's five-year retention rule.

How is the tax you withhold actually calculated?

Thai salary withholding works by annualising. Each month you project the employee's pay across the full year, deduct their expense allowance and personal deductions, run the result through the progressive rate table, and divide the annual tax across the pay periods. The first THB 150,000 of net income is exempt and the top 35% rate starts only above THB 5 million of net income.

Two practical consequences follow. First, variable pay changes the withholding amount in the month it is paid. For occasional special payments such as bonuses, Revenue Department Order Por. 96/2543 prescribes an annualisation method that withholds the increment in that month; regular commissions are treated according to the way they are actually paid. Second, the employer bears the risk of under-withholding — the Revenue Code makes an employer that withholds too little liable for the shortfall together with the employee. The monthly PND.1 records what you actually deducted; the year-end summary is where the totals must reconcile.

How much is social security in 2026 — and where is the ceiling going?

Contributions are 5% of monthly wages from the employee, matched by 5% from the employer, calculated on wages between THB 1,650 and THB 17,500 per month. The ceiling rose from THB 15,000 to THB 17,500 on 1 January 2026 under a ministerial regulation published in December 2025, lifting the maximum contribution from THB 750 to THB 875 each side. A 2026 pay run that still caps the deduction at THB 750 is wrong.

The increase is staged across three periods:

• 2026–2028: contributions calculated on wages up to THB 17,500/month — maximum THB 875 each side.
• 2029–2031: ceiling rises to THB 20,000/month — maximum THB 1,000 each side.
• 2032 onwards: ceiling rises to THB 23,000/month — maximum THB 1,150 each side.

At the current statutory rate of 5% for both sides, those ceilings produce the maximums above; future regulations or temporary relief measures may change the applicable rate. In return, registered employees are covered across the SSO's seven benefit branches, from sickness and maternity to old age and unemployment.

Which payroll obligations run annually rather than monthly?

Five dates anchor the annual layer, four of them in the first quarter:

• By 31 January — Workmen's Compensation Fund: an employer-only contribution covering work-related injury and illness, charged at 0.2% to 1.0% of estimated annual wages depending on your business's risk classification — a rate that can later be adjusted for your own claims record — with each employee's wages counted up to THB 240,000 per year. In the first year, the contribution is due within 30 days of the employer first having one or more employees — completing the registration does not start a fresh 30-day period.
• Within January — the employment-conditions disclosure: employers with 10 or more employees must submit the Employment Terms and Working Conditions Disclosure Form — the Kor Ror 11 — to the Department of Labour Protection and Welfare within January each year, under section 115/1 of the Labour Protection Act.
• By 15 February — 50 tawi certificates: every employee receives a withholding-tax certificate for the previous year. An employee who left during the year must receive theirs within one month of leaving.
• Within February — PND.1 Kor: the annual summary filed with the Revenue Department, covering every employee paid during the year — including staff whose pay was too low for any tax to be withheld.
• February to 31 March — Workmen's Compensation true-up: you report the wages actually paid the previous year, and any shortfall against January's estimate is payable by 31 March.

Your employees then file their own personal returns, PND.90 or PND.91, by 31 March — online filers typically get longer, 8 April 2026 for tax year 2025, with the extension announced year by year — and the 50 tawi you issued is the supporting evidence for that return.

What about provident funds and the Employee Welfare Fund?

A provident fund is optional but common in professional workplaces. If you offer one, it must be a registered fund run by a licensed fund manager; under Section 10 of the Provident Fund Act both the employee's savings and the employer's contribution ordinarily sit between 2% and 15% of wages, at rates set by the fund's own rules rather than a one-for-one match, and the employer must remit both to the fund within three working days of paying wages — not merely at month-end.

The Employee Welfare Fund is the statutory fallback for employers without a registered provident fund. Collections are scheduled to begin on 1 October 2026 for employers with 10 or more staff: the employer and the employee each contribute 0.25% of wages from 1 October 2026 to 30 September 2031, rising to 0.50% each from 1 October 2031. An employer that already provides a registered provident fund generally sits outside the statutory fund — confirm the exemption covers the employees concerned before relying on it.

What changes when you employ foreign staff?

For payroll, employing foreign staff changes less than most employers expect. A foreign employee may work under the Non-Immigrant B visa and work permit route or another qualifying work-authorisation regime — BOI and Long-Term Resident routes among them — so confirm each person's authorisation before the first day. Once lawfully employed and within Section 33 coverage, they are registered with the SSO on the same SSO 1-03 form, within the same 30 days, and contribute the same 5% up to the same THB 17,500 ceiling. Withholding normally follows the ordinary progressive rules unless a specific tax incentive applies: qualifying LTR Highly Skilled Professionals may receive a 17% rate on qualifying employment income, and separate regimes — including the International Business Center (IBC) regime for qualifying expatriates — can provide different treatment. BOI promotion by itself does not automatically create a special personal-tax rate, so confirm the employee's exact incentive before the first pay run.

One additional duty applies under the Royal Ordinance on the Management of Foreign Workers' Employment: you must notify the Department of Employment within 15 days when a foreign employee starts or stops working for you, with a fine of up to THB 20,000 for missing it. This notification is easy to overlook because it sits outside the SSO and Revenue Department payroll cycles.

Where do leave, severance and the rest of labour law fit in?

Payroll executes what labour law promises, so the two systems must agree. Maternity leave is now 120 days per pregnancy with 60 days employer-paid, an employee whose spouse has given birth is entitled to up to 15 days of paid leave — the leave itself must be taken within 90 days from the date of birth, though the request may be made in advance — severance on a qualifying dismissal runs from 30 days' wages after 120 days of service to 400 days after 20 years, and the daily minimum wage ranges from THB 337 to THB 400 by province and business type under Wage Committee Notification No. 14, in force since 1 July 2025. We do not repeat those rules here. Our guide to the 2026 labour-law amendments covers what changed, what is still in draft and the employer checklist. If your leave policies predate December 2025, start there.

What are the penalties for late filing or underpayment?

Each authority applies its own late-payment regime — the surcharge rates are expressed per month, but the underlying filing cycles are not all monthly:

• PND.1 — Revenue Department: late remittance costs a surcharge of 1.5% per month of the tax due, with a part-month counted as a full month and the accrued surcharge capped at the tax due itself, plus a fine of up to THB 2,000 for the late return itself. Tax you failed to withhold remains collectible from you, jointly with the employee.
• Social security — SSO: unpaid contributions attract 2% per month, counted from the day after the 15th. Intentional registration failures are a separate, criminal matter: up to six months' imprisonment or a fine of up to THB 20,000, or both.
• Workmen's Compensation Fund: unpaid contributions carry a statutory monthly surcharge under the Workmen's Compensation Act — confirm the current rate with the SSO before settling an arrears calculation.

The pattern to notice: late-remittance surcharges follow the employer's own remittance duty and accrue automatically from the missed date, though liability for the underlying tax can differ where the tax was never withheld in the first place. Criminal liability — such as the intentional registration offence — is a separate category with its own legal elements. Repeatedly late monthly payroll accumulates the PND.1 and social-security charges; a Workmen's Compensation surcharge arises separately, only when a contribution due under its annual cycle goes unpaid.

When does outsourcing payroll make sense?

When the loop above costs more attention than it is worth running in-house. Three situations come up repeatedly:

• No Thai-reading finance function: the statutory forms, portals and authority correspondence — PND.1, SPS 1-10, the annual layer — are predominantly Thai-language.
• Salary confidentiality: in a small office, whoever runs payroll knows every salary. An external payroll team keeps pay data outside your own office.
• Crossing the 10-employee line: at 10 staff the obligations step up — written work rules, the January disclosure filing, the Employee Welfare Fund from 1 October 2026 — and the cost of a missed step rises with headcount.

If that is where you are, our payroll outsourcing team runs the full monthly and annual cycle described in this guide; HR administration owns the contracts, work rules and leave records around it; and our accounting and tax packages bundle payroll with bookkeeping and the company's own tax filings. Whichever way you run it, every date above needs an owner.

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This article is general guidance — not legal or tax advice. If you'd like a scoped opinion on how it applies to your specific situation, contact our team.