Thailand payroll compliance in 2026: PND.1, Social Security and the monthly close

The Revenue Department calendar shows PND.1 among the withholding returns due after the payment month, while the Social Security process has its own due date and portal. These are external endpoints, not suitable internal cutoffs. Mark the current dates in the Thailand tax calendar, then set earlier deadlines for employee changes, manager approval and bank release.

Link payroll to the wider monthly tax filing workflow, but keep ownership explicit. A tax preparer cannot repair an unapproved bonus, incorrect employee status or changed bank account on filing day.

• HR change cutoff and named approver.
• Payroll calculation and exception review date.
• Bank file approval and payday.
• PND.1, Social Security, ledger and evidence completion dates.

PND.1 covers tax withheld from employment and specified personal-service income. Employment withholding is not a single flat percentage copied across employees: the calculation depends on the Revenue Code method, expected annual income and the employee information available to the employer. Bonuses, irregular pay, termination payments and mid-year starts therefore need deliberate treatment.

Reconcile the return to taxable payroll before submission. The official form separately identifies ordinary employment, approved 3% cases, termination lump sums and Section 40(2) payments. Where the facts are unclear, route the item through the tax compliance review instead of forcing it into last month’s category.

For Section 33, the 2026–2028 maximum wage base is THB 17,500. At the standard 5% rate, the maximum employee contribution and matching employer contribution are THB 875 each per month. This changed from the former THB 15,000 ceiling, so old spreadsheets can understate both deductions and employer cost.

Do not assume every month and location follows the headline rate. The Ministry of Labour announced a temporary 3% rate from December 2025 through May 2026 for employers and insured persons in nine flood-affected southern provinces. That period has ended, but it demonstrates why the payroll file should record the rule actually applied. Confirm employee registration, changes and the month’s effective notice through the official employer channel and the Thailand accounting requirements guide.

A payroll can be arithmetically correct and still fail operationally. Compare current totals with the prior month and headcount, list every material movement, confirm the bank total equals approved net pay and prove that tax and Social Security liabilities equal the filed amounts. The ledger should split salary, benefits, employer contribution, withholding and payable balances clearly enough to clear them later.

Restrict access to employee and bank data, separate preparation from approval and log late changes. For a growing team, document these controls before volume makes exceptions invisible; the startup and SME accounting page shows where payroll fits into the broader finance routine.

• Headcount, gross pay and net pay variance against the prior month.
• New or changed bank accounts independently confirmed.
• PND.1 and SSO totals tied to the payroll register.
• Bank release tied to approved net pay and the ledger posting.

Year-end work should not require rebuilding twelve months. Maintain employee identifiers, cumulative income, benefits, deductions and withholding every month. The Revenue Code requires an employment withholding certificate generally by 15 February of the following year, or within one month after employment ends during the tax year; annual employer reporting also depends on clean cumulative data.

Before issuing certificates, reconcile the annual total to all monthly PND.1 filings and the general ledger. Record corrections by payroll month rather than overwriting history. This preserves a trace from an employee’s certificate to the return, payment and accounting entry.

Recurring errors usually come from process gaps: HR sends changes after calculation, a bonus is approved only in chat, a leaver remains active, Social Security uses the old ceiling, or payroll liabilities stay uncleared in the ledger. Re-running a spreadsheet does not solve missing authorization or conflicting source data.

Keep one employee master, one controlled change log and one final register. If prior payrolls contain mismatches, separate the current month from remediation, quantify each affected period and preserve the original filed evidence before making corrections.

Request a review when hiring the first employee, moving payroll in-house or between providers, adding foreign staff, changing compensation, finding uncleared liabilities or preparing year-end certificates from incomplete data. Provide the employee list, contracts and amendments, recent registers, filings, payment evidence and ledger balances.

A useful review starts with the data trail, not only the payslip format. Send the current payroll setup for review and identify the next payday and filing month so the immediate risk can be separated from longer-term cleanup.