Thailand 50 Bis Certificate: Why Foreign Employees Need It

For many foreign employees, the first encounter with a 50 Bis is an email from HR after year-end or shortly after leaving a job. The Thai document is a withholding tax certificate: it identifies the payer and the income recipient, then records the relevant income and the tax withheld at source. In an employment context, it is the employer’s record of what it paid and what it withheld for that employee.

The official form is more specific than a generic salary statement. It contains payer and taxpayer identification fields, a category for salary and wages under Section 40(1), the amount paid, the tax withheld, and spaces for certain fund contributions. That makes it a reconciliation document. A year-end bonus, an adjustment in final payroll, or a payment made after notice was given can all create a mismatch between what an employee remembers receiving and what the certificate reports.

A 50 Bis is not a tax-clearance certificate. It does not decide whether someone is a Thai tax resident, it does not replace an annual return where filing is required, and it does not establish that withholding equals the final annual liability. Withholding is part of the collection process; the year-end result can still be tax payable, tax overpaid, or an amount that happens to match the withholding already made.

That distinction becomes especially useful after a job change. One certificate tells you about one payer’s figures. It does not silently absorb income from another employer, and it cannot answer by itself whether P.N.D.91, P.N.D.90, or another filing position applies to the person’s full set of income for the year.

For employment income, the timing is set by Section 50 Bis of the Thai Revenue Code, not by an employer’s preferred payroll calendar. Where employment continues through year-end, a certificate for withholding under Section 50(1) is due by 15 February of the following year. An employer may deliver it earlier, but an internal promise such as “with January payroll” is not the statutory rule.

A different deadline applies when employment ends during the tax year. The certificate is then due within one month from the termination date. Someone who leaves in June does not have to wait until the following February, yet the law also does not mean every employer must hand over the document on the employee’s final afternoon. If the employee is leaving Thailand soon afterwards, it is worth arranging a personal email address and a named HR or payroll contact before company access is closed.

Changing jobs creates two separate records. The former employer remains responsible for its own certificate, while the new employer reports its own payments and withholding. A new payroll team may ask for prior-year or prior-employer information for administrative reasons, but it does not automatically recreate the old employer’s 50 Bis.

The practical timing issue is therefore less about chasing HR on a guessed date and more about knowing which deadline applies. A year-end employee and a mid-year leaver are on different statutory clocks. Keeping that distinction clear makes it much easier to spot when a certificate is genuinely late rather than merely still inside the employer’s permitted issuance period.

With one employer and only Section 40(1) employment income for the year, a 50 Bis is the natural starting point for reconciling an annual return. P.N.D.91 is expressly designed for taxpayers whose income is only from employment under Section 40(1), and the form includes a line for withholding tax. The certificate therefore gives the payer-side figures that can be checked against payslips and the employee’s own records before filing.

A job change breaks that tidy one-employer chain. The former employer issues a certificate for its own payments; the new employer issues another for its own. Payroll onboarding at the second company does not transfer the first company’s tax certificate into the new system. If the former employer’s document is missing, the gap may only become obvious much later, after corporate email has been disabled and familiar HR contacts have moved on.

With two employers, the annual picture is assembled from both certificates. Imagine one certificate covering January through May and a second covering June through December. The second document does not supersede the first simply because it is newer. Any final bonus, severance-related payment, or payroll adjustment also needs to be matched to the certificate that reports it so income and withholding are not counted twice or left out.

P.N.D.91 should not be treated as the default form for every foreign employee. The Revenue Department describes it as the return for a taxpayer with only employment income under Section 40(1). A person who also has income in other categories may instead fall into the P.N.D.90 filing framework or another fact-specific position. The certificate records a payer’s withholding; it does not choose the annual return.

Nor does the withholding figure settle the final tax calculation by itself. Annual tax can differ once total income, deductions, allowances, credits and other applicable items are taken into account. That is why the 50 Bis is most useful as a reliable input into the year-end reconciliation. Filing obligations and the correct return still depend on the employee’s actual income profile and the rules applicable to that tax year.

A missing 50 Bis often starts as an administrative problem rather than a tax dispute. The certificate may have been sent to an old email address, still be in the employer’s payroll queue, or be waiting with the wrong HR contact. A useful request identifies the employee, taxpayer number if available, employment period, termination date where relevant, and exactly which certificate is missing. That gives the employer a concrete record to trace.

When the certificate exists but looks wrong, describe the discrepancy rather than asking for a vague review. Common examples include the wrong name or taxpayer ID, the wrong tax year, a missing bonus, incomplete income, or withholding that does not match payroll records. Editing the PDF yourself is not a correction. The payer needs to issue a corrected or replacement certificate so the document still represents the payer’s certified figures.

Keep the original version, the corrected version, and the correspondence explaining the change until the filing position is settled. This is particularly useful after changing jobs, when similar-looking certificates from two employers can otherwise be confused months later. Clear file names and employment periods are a small administrative habit that prevents a surprisingly common reconciliation mess.

If a former employer has gone beyond the Section 50 Bis deadline, the issue is no longer simply whether internal payroll is running late. After a written follow-up, the Revenue Department is the appropriate official point for confirming the current escalation route. There is no reason to invent a universal complaint form where the official source has not established one; the process and supporting evidence should be checked against the department’s current instructions.

For a lost certificate, the practical route is also back to the issuer. Ask the employer or other payer for another copy instead of reconstructing the document yourself. Any current requirements for format, evidence or use with an electronic filing should be confirmed from the Revenue Department for the relevant tax year.