What can make the amount go up?
Almost any money you receive because of your job is employment income under section 40(1) of the Revenue Code, but some items have exemptions of their own. [1]
Overtime
Pay for working beyond normal hours or on holidays. The amount depends on the hours actually worked in the period. It is employment income and tax on it is taken in the month it is paid. [1][2]
Commission
A share of sales or results on agreed terms. When it is not paid every month, tax on it is taken in the month it arrives, under Order P. 96/2543, not averaged over the year. [1][2]
Bonus
The Revenue Code names bonuses as section 40(1) income. A bonus month has more tax taken than usual because the whole increase in tax is withheld in that month. [1][2]
Allowances
Allowances, position pay and housing money are section 40(1) income, but some items are exempt under conditions: allowances or transport money spent entirely on carrying out your duties, travel allowances at government rates, and travel to take up a job for the first time. Ask Payroll how each item is treated. [1]
Other employment benefits
For example, a home your employer lets you live in rent-free, or a debt of yours that your employer pays. The law counts these as employment income even though no cash reaches your account. [1]
What can be deducted from a payslip?
The Labour Protection Act forbids an employer from deducting wages, overtime pay, holiday pay or holiday overtime pay except for the purposes section 76 lists. An employer cannot deduct whatever it likes. [5]
Withholding tax
- What is it?
- Income tax your employer takes from each payment in advance and pays to the Revenue Department for you.
- Why is it deducted?
- Section 50(1) of the Revenue Code makes the payer withhold every time it pays, by treating the payment as if paid all year and dividing by the number of periods. It is not the year’s tax divided by twelve, so months with extra pay have more taken.
Social security (your share)
- What is it?
- Your contribution to the Social Security Fund as a section 33 insured employee.
- Why is it deducted?
- Employee and employer each pay the same rate: normally 5% of wages each, counting wages only up to a ceiling set by ministerial regulation. Some periods and areas have had temporary cuts, such as 3% a side in nine southern provinces for December 2568 to May 2569.
Provident fund savings
- What is it?
- Your own savings, deducted only if your employer has a fund and you joined it.
- Why is it deducted?
- You pay savings and your employer pays contributions at the rates in the fund’s rules, and the Labour Protection Act allows savings under a fund agreement to be deducted.
Other deductions the law allows
- What is it?
- Labour union dues; debts to a savings cooperative or for welfare that benefits only the employee; a security deposit; or damages the employee caused wilfully or by gross negligence.
- Why is it deducted?
- Section 76 allows only these. Cooperative debts need your consent in advance and damages need your consent. Each may be at most 10%, and together at most one fifth, of what you are due for the period, unless you agree otherwise.
- What should I check on my payslip?
- Whether there is a consent you signed, or a specific agreement (section 77), and whether the total is within the limits. [5]
Keep these apart
- Your deductions vs your employer’s contributions
- The employer’s share is the company’s own money, paid on top. It is not taken from your pay.
- Monthly withholding vs the year’s tax
- Monthly amounts are taken in advance. The real tax is worked out for the whole year on the PND91 return and what was withheld is credited, so you may owe more or have paid too much.
- Provident fund savings vs tax
- Your savings are still yours, held in the fund. None of it goes to the government.
- An advance or adjustment vs a statutory contribution
- An advance is your own pay, paid early; an adjustment corrects an earlier period. Neither is a payment the law requires, and you can ask for an itemised explanation.
Why is this month different?
The table holds the same figures as the payslip above: four months of the same person.
Scroll the table sideways to see the other months.
| Line | Normal month | Commission | Bonus month | Part paid early |
|---|---|---|---|---|
| Base salary | 35,000.00 | 35,000.00 | 35,000.00 | 35,000.00 |
| Other pay | 0.00 | 6,000.00 Commission | 70,000.00 Bonus | 0.00 |
| Gross earnings | 35,000.00 | 41,000.00 | 105,000.00 | 35,000.00 |
| Withholding tax | −368.33 | −668.33 | −4,288.33 | −368.33 |
| Social security (your share) | −750.00 | −750.00 | −750.00 | −750.00 |
| Provident fund savings | −1,050.00 | −1,050.00 | −1,050.00 | −1,050.00 |
| Net pay | 32,831.67 | 38,531.67 | 98,911.67 | 32,831.67 |
| End of month | 32,831.67 | 38,531.67 | 98,911.67 | 22,831.67 + 10,000.00 mid-month |
Pay that does not come every month, such as a bonus or commission, appears only in the month it is paid. It is not spread over the year. [2]
- Normal month
- Nothing extra, so gross earnings equal the 35,000.00 salary. Tax, social security and fund savings take off 2,168.33, leaving 32,831.67, paid in one transfer at the end of the month.
- Commission
- A 6,000.00 commission lifts gross earnings to 41,000.00. This month’s tax rises by 300.00 because tax on the commission is taken in the month it is paid, not spread over the year. Overtime works the same way.
- Bonus month
- The 70,000.00 bonus carries 3,920.00 of extra tax, all in this month: the increase in the year’s tax that the bonus causes. The year’s actual tax is settled on the PND91 return.
- Part paid early
- The payslip still shows net pay of 32,831.67, as in a normal month, but 10,000.00 was advanced mid-month, so the end-of-month deposit is 22,831.67. Nothing went missing; it arrived in two transfers.
Joining or leaving during a pay period
The first or last period pays only the time worked. The method depends on your contract and your employer’s lawful practice, so this example has no figures for it.
Withholding for someone who joins mid-year is worked out over the periods left in the year. In a leaver’s last month the employer may recalculate with the allowances the employee has proved. [2]
A payslip checklist
- Is the pay period right?Check the start and end dates, especially in your first and last month.
- Is the base salary right?Compare it with your contract or latest salary letter.
- Is all the extra pay there?Overtime, commission, a bonus or other pay due for this period.
- What does each deduction mean?If you cannot tell what a line is, you can ask.
- Does net pay match what reached your bank?Compare it with the deposits for the same period.
- Was anything paid separately?For example an advance, an expense refund or a split payment.
- Who should I ask if it does not match?Payroll or HR. Ask for an itemised explanation; your employer’s records explain your case.
Compare your payslip with your employment terms and your bank deposits. If something still does not match, send Payroll or HR an itemised question. There is no need to show your payslip or bank statement to anyone outside your employer.
Tools for the next step
Questions and answers
Why is so much tax taken in a bonus month?
Because the extra tax the bonus causes is withheld in that one month. In the example, a 70,000.00 bonus carries 3,920.00 of extra tax. The year’s actual tax is still settled on the PND91 return. [2][4]
Is the employer’s social security taken from my pay?
No. The employer pays its own share on top, at the same rate as yours. Your payslip should show only your share as a deduction. [6]
Why does my bank deposit differ from the net pay on my payslip?
Separate transfers, an advance, payment in instalments, or an adjustment from an earlier period. Your employer’s records explain your case.
Is the tax withheld during the year my final tax?
Not yet. The real tax is worked out for the whole year on the PND91 return and the tax withheld is subtracted, so you may owe more or have paid too much. [4]
Sources
Read on Thai government websites; the date is when the author last opened each one.
- Revenue Code, sections 40(1), 42(1)–(3), 42 bis, 50(1) and 50 bis (Revenue Department)Applies to: Current text as published · Checked
- Revenue Department Order P. 96/2543: withholding tax on employment income under section 50(1), with examplesApplies to: In force; the example uses tax-year 2568 rates and allowances · Checked
- Revenue Department: PND91 filing instructions, tax year 2568 (expenses, allowances, provident fund, rates)Applies to: Income received in 2568 (2025) · Checked
- Revenue Department: PND91 form, tax year 2568 (tax withheld is credited against the year’s tax)Applies to: Tax year 2568 · Checked
- Labour Protection Act B.E. 2541, sections 76–77, consolidated by the Office of the Council of State to Act No. 7 B.E. 2562 (published by the Ministry of Labour)Applies to: Consolidated text to 2562 (2019) · Checked
- Government Public Relations Department (Ratchaburi), 2 Jan 2569: Cabinet cuts section 33 contributions from 5% to 3% a side in nine southern provinces, Dec 2568 – May 2569Applies to: Normal rate before the cut; the cut covers Dec 2568 – May 2569 in those provinces · Checked
- Social Security Office, list of ministerial regulations: includes the 2568 regulation setting the minimum and maximum wages used to calculate section 33 contributionsApplies to: Title checked; the document could not be opened (download page under maintenance on 6 Nov 2026) · Checked
- Office of the Council of State, opinion 692/2546, quoting the Provident Fund Act B.E. 2530, sections 3 and 5 (employee savings and employer contributions)Applies to: Sections as quoted in 2546 (2003) · Checked
What this article does not do
It does not work out your year’s tax, it does not use any year’s social security wage ceiling, and it does not decide your case. Your employer’s records and agreements are the explanation that counts.