How to Calculate Payroll in Thailand: Step-by-Step Guide (SSO, PIT, Withholding Tax)

If you’ve ever stared at a Thai payroll spreadsheet wondering what all those deduction columns actually mean — you’re in good company. Whether you’re an HR manager at a Bangkok SME, a business owner with a growing team, or an expat running Thai operations for the first time, understanding how to calculate payroll in Thailand is one of those things you simply can’t afford to get wrong.

Thai payroll involves three interconnected layers: Social Security contributions (SSO), Personal Income Tax (PIT), and Withholding Tax. Each has its own rates, caps, deadlines, and compliance rules. Miss one, and you’re looking at penalties from either the Social Security Office (SSO Office) or the Revenue Department. This guide walks you through the whole process, step by step.

Payroll in Thailand isn’t just a finance function — it’s a legal obligation. The Labour Protection Act B.E. 2541, combined with Revenue Department regulations and Social Security Act requirements, sets strict standards for how employees must be compensated and how deductions must be handled.

For expats and foreign-owned businesses, the stakes are even higher. Tax treaties, work permit conditions, and PDPA (Personal Data Protection Act) compliance add extra layers that don’t exist in many home countries. A well-configured Payroll system tailored to the Thai regulatory environment can save you from costly compliance surprises.

Before diving into the calculations, it helps to understand what “payroll” actually includes in the Thai context:

Base Salary — The fixed monthly amount agreed in the employment contract. Thailand’s minimum wage currently ranges between 400–400+ THB per day depending on province.

Additional Earnings — Overtime pay (OT), performance bonuses, position allowances, transportation or meal allowances, and commissions. All of these count as assessable income for tax purposes.

Deductions — Social Security contributions, Provident Fund contributions (if applicable), and Withholding Tax. These reduce the gross pay to arrive at the employee’s net pay.

Thailand’s Social Security Fund (กองทุนประกันสังคม) requires contributions from both employee and employer each month. Here’s how it works:

• Employee contribution rate: 5% of monthly salary
• Employer contribution rate: 5% of monthly salary
• SSO salary cap: ฿15,000/month (regardless of actual salary)
• Maximum monthly deduction per employee: ฿750

Example: An employee earning ฿50,000/month — SSO is calculated on the capped base of ฿15,000, so ฿750 is deducted from the employee’s gross pay, and the employer contributes another ฿750.

Deadline: SSO must be submitted by the 15th of the following month. Late payment incurs a 2% surcharge per month on the outstanding amount.

Automating this with a purpose-built Thai payroll platform eliminates the manual tracking of which employees hit the cap and when — particularly useful if you have part-time staff or staff who joined mid-month.

Thailand uses a progressive Personal Income Tax system — the more an employee earns, the higher the rate they pay on the upper portions of their income. The current tax brackets are:

Calculating Net Income:

Net Income = Gross Income − Allowable Expenses − Personal Allowances

Allowable Expenses: Employees can deduct 50% of their income as employment expenses, capped at ฿100,000/year.

Common Personal Allowances:

• Personal allowance: ฿60,000/year
• Spouse (no income): ฿60,000
• Children: ฿30,000/child (up to 3 children, or ฿60,000/child for the 2nd child onwards if born from 2018)
• Social Security contributions: actual amount paid
• Life insurance premiums: up to ฿100,000/year
• LTF/RMF funds: subject to specific conditions

Withholding Tax is the mechanism by which employers deduct estimated income tax from employees every month and remit it directly to the Revenue Department. Think of it as pay-as-you-earn — the employee doesn’t have to worry about saving up for a large year-end tax bill.

Monthly Withholding Tax Calculation:

1. Annualise income: Monthly gross pay × 12
2. Deduct expenses: 50%, capped at ฿100,000
3. Deduct personal allowances: All applicable ones
4. Calculate annual tax: Apply progressive brackets
5. Divide by 12: This is the monthly Withholding Tax to deduct

Filing deadline: By the 7th of the following month (or the 15th if filing electronically via the Revenue Department’s e-Filing system)

If Withholding Tax is under-deducted, the employer is liable for the shortfall — not the employee. Getting the calculation right from month one matters.

Once you have all the components, the net pay calculation is straightforward:

Net Pay = Gross Pay − SSO Deduction − Withholding Tax − Other Deductions (e.g. Provident Fund)

Real-world example:

• Gross salary: ฿45,000
• SSO deduction: ฿750
• Provident Fund (5%): ฿2,250
• Withholding Tax (estimated): ฿2,000
• Net pay: ≈ ฿40,000

Employees receive a pay slip (ใบแจ้งเงินเดือน) that details every component. Under Thai labour law, employers are required to provide this — and it should be clear enough for the employee to verify the numbers themselves.

Running payroll in Thailand gets complex fast, especially as your team grows. These tips will keep you on track:

1. Update rates every fiscal year. The SSO Office and Revenue Department periodically adjust contribution rates and allowance thresholds. Missing an update means under- or over-deducting from day one of the new year.
2. Keep records for at least 5 years. Pay slips, tax filings (ภ.ง.ด.1 and ภ.ง.ด.1ก), and SSO contribution records must be retained. Sprout Keeper provides a secure, PDPA-compliant document vault for exactly this purpose.
3. Connect attendance data directly to payroll. OT pay can’t be calculated accurately without reliable attendance records. Integrating your attendance system with your payroll platform eliminates manual data transfer and the errors that come with it.
4. Manage leave balances before running payroll. Unused leave encashment or unpaid leave deductions affect gross pay and therefore tax calculations. A connected leave management system keeps these numbers accurate.
5. Always run a preview before approving. No matter which system you use, treat every payroll cycle with a preview-then-approve workflow. Catching errors before payout is always better than reversals.

Sprout Payroll is built specifically for the Thai compliance environment — not adapted from a generic global platform. Here’s what makes it stand out for Thai businesses and international companies operating in Thailand:

• Automated SSO, PIT, and Withholding Tax calculations — rates, caps, and brackets are maintained and updated within the system
• Pay slip generation and ภ.ง.ด.1 filing support — employees get digital pay slips; HR gets ready-to-file tax documents
• Native integration with Leave and Attendance modules — data flows automatically across the HR stack
• PDPA-compliant data architecture — salary data is protected according to Thai data protection law
• Multi-entity support — manage payroll for multiple companies or legal entities within a single dashboard
• Thai-language interface and Thai tax logic — no workarounds, no custom configuration needed

Whether you’re running payroll for 20 employees or 2,000, the same rigour applies. Book a demo to see how Sprout handles your specific payroll structure.

How do I calculate payroll in Thailand step by step?

The core steps for calculating payroll in Thailand are: (1) determine gross pay including all allowances, (2) calculate the SSO deduction (5% of salary, capped at ฿750/month), (3) compute Withholding Tax based on annualised income minus applicable allowances and expenses, and (4) subtract all deductions to arrive at net pay. A payroll system like Sprout handles all four steps automatically.

What is the Social Security (SSO) rate in Thailand?

Both employer and employee contribute 5% of the employee’s monthly salary, based on a salary cap of ฿15,000/month. This means the maximum deduction from an employee’s pay is ฿750/month, regardless of their actual salary. The employer matches this with their own ฿750 contribution per employee.

What is the difference between Withholding Tax and Personal Income Tax in Thailand?

Withholding Tax (WHT) is deducted monthly by the employer and remitted to the Revenue Department — it’s a prepayment of Personal Income Tax (PIT). At year-end, the employee files a personal tax return (PND 91) to reconcile the total. If WHT was over-deducted, they get a refund; if under-deducted, they pay the difference.

When must I submit SSO and Withholding Tax in Thailand?

SSO contributions must be submitted by the 15th of the following month. Withholding Tax (PND 1) must be filed by the 7th of the following month, or the 15th if filing electronically. Both carry penalties for late submission.

Do foreign employees in Thailand pay the same taxes as Thai employees?

Foreign employees who are tax residents of Thailand (present for more than 180 days in a calendar year) are subject to the same progressive PIT rates. Some may benefit from Double Taxation Agreements (DTAs) between Thailand and their home country, which can reduce or eliminate certain taxes. Consulting a tax advisor is strongly recommended for international hires.

Is a Provident Fund mandatory in Thailand?

The Provident Fund is not mandatory, but once an employer establishes one, eligible employees must enrol. Employer contribution rates range from 2% to 15% of the employee’s salary; employees contribute between 2% and 15% as well. Contributions are tax-deductible for both parties up to specified limits.

Can I run Thai payroll in Excel?

Technically yes, but it becomes increasingly risky as headcount grows. Manual spreadsheets are prone to formula errors, are difficult to audit, and can’t automatically incorporate regulatory updates. For teams of 20+ employees, a dedicated Thai payroll system like Sprout provides compliance assurance that spreadsheets simply can’t match.

What documents must employers provide to employees in Thailand?

Thai employers must provide a pay slip (ใบแจ้งเงินเดือน) each pay period and a withholding tax certificate (ใบรับรองการหักภาษี ณ ที่จ่าย / 50 ทวิ) at year-end. The annual tax reconciliation form ภ.ง.ด.1ก must be filed with the Revenue Department by the end of February each year.

How to calculate payroll in Thailand is no small task — but it becomes significantly more manageable with the right system, the right knowledge, and a process that keeps compliance built in rather than bolted on. Whether you’re standardising your existing process or setting up payroll from scratch, the investment in getting it right pays off every single month.

Ready to automate your Thai payroll? Explore Sprout Payroll Want to see it in action? Book a free consultation with our team — no commitment required.

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