Key takeaways
- Agree in writing which firm files each return for the handover month, starting with the withholding tax returns due on the 7th and the VAT return due on the 15th.
- The company should own its Revenue Department e-Filing access; credentials should be changed and controlled by a director or the finance lead.
- Collect the general ledger, filed returns with payment receipts, withholding tax certificates and the last audited financial statements before the engagement ends.
- Avoid switching between fiscal year end and the AGM unless year-end close and audit support are assigned in writing.
- If a return slips, file it quickly, because the 1.5% monthly surcharge keeps running on unpaid tax.
About the Author
This guide was prepared by the Business Operations team at Settlr Global, led by Managing Director Gagan Ajmani, who has 15+ years of regional experience across Southeast Asia. The team takes over books, filing calendars and e-Filing access from previous providers for foreign-owned and Thai-owned companies in Bangkok.
Why do filings get missed when a company changes accounting firm?
Missed filings during a switch generally come from unclear ownership of a tax calendar that keeps running while the handover is underway. Withholding tax in Thailand is filed monthly by the 7th of the following month, and VAT by the 15th, so any handover lasting a few weeks will cross at least one deadline.
Consider an engagement that ends on 31 March. The March PND.1, PND.3 and PND.53 returns fall due in early April, followed by PP.30. The old firm holds the March vouchers; the new firm holds the signed engagement letter.
Foreign-owned companies carry an extra layer of risk: directors are often overseas, signatures take longer and e-Filing credentials may sit in the old firm's inbox. The practical fix is to list every return due in the 60 days after the switch and put one firm's name against each.
Which Thai filings are at risk during an accounting handover?
The filings at risk are the recurring monthly returns plus any annual return whose preparation straddles the switch, with deadlines set by the Revenue Department11Revenue Department of Thailandrd.go.th and the Department of Business Development (DBD).22Department of Business Development, Ministry of Commercedbd.go.th The table below sets out the common ones.
1Revenue Department of Thailandrd.go.th
2Department of Business Development, Ministry of Commercedbd.go.th
| Filing | Form | General deadline | Handover question |
|---|---|---|---|
| Withholding tax on salaries | PND.1 | 7th of the following month | Is payroll moving at the same time? |
| Withholding tax on payments to individuals | PND.3 | 7th of the following month | Who holds the payment vouchers? |
| Withholding tax on payments to companies | PND.53 | 7th of the following month | Who issues the withholding tax certificates? |
| VAT return | PP.30 | 15th of the following month | Who has the input and output tax reports? |
| Social security contributions | Social Security Office monthly filing | 15th of the following month, under the Social Security Act B.E. 25333 | Who has the SSO e-service login? |
| Annual corporate income tax | PND.50 | Within 150 days of fiscal year end | Who prepares the year-end close? |
| Half-year corporate income tax | PND.51 | Half-year estimate; confirm the current date | Who prepares the six-month projection? |
| Audited financial statements | DBD filing | Within one month after the AGM, which is held within four months of year end | Who supports the auditor? |
The extension period should be confirmed for the current year before a handover plan relies on it.
When is the safest time to switch accounting firms in Bangkok?
The safest switch point is the start of a month, after the old firm has filed the previous month's returns, because monthly deadlines never pause. Year end is not ideal; the period after year end is the heaviest compliance stretch of the year.
After year end, the books are closed, the audit is completed by a certified public accountant in Thailand, the AGM approves the statements, the DBD filing follows and corporate income tax in Thailand is filed on PND.50. A new firm taking over in that window has to close a year it never booked.
A company should either let the outgoing firm finish the year-end close and audit support, or assign that responsibility and fee in the new engagement letter.
What records should a company collect from its old accounting firm?
Under Section 14 of the Accounting Act B.E. 2543 (in Thai),44dbd.go.thdbd.go.th companies should generally keep their accounts and supporting documents for at least five years, and those records belong to the company. Request these while the old team still has the context to answer questions:
4dbd.go.thdbd.go.th
- General ledger export and trial balance at the cut-off date
- Filed PND.1, PND.3, PND.53 and PP.30 returns with payment receipts
- Copies of withholding tax certificates issued and received
- Input and output VAT reports
- Filed PND.50 and PND.51 returns
- Last audited financial statements, audit report and DBD filing receipt
- Fixed asset register and depreciation schedule
- Social Security Office contribution records
- Any open Revenue Department letters or assessments
How is Revenue Department e-Filing access transferred?
The company should treat its e-Filing account as its own asset, with credentials controlled by a director or the finance lead.
- The old firm's tax agent appointment is revoked in the e-Filing system.
- Social Security Office e-service access is updated in the same week.
Foreign directors should sign these documents early, since courier and notarisation time sits inside the handover window.
What does a step-by-step accounting handover look like?
The handover generally follows this sequence:
- Step 1: List every return due in the next 60 days using a calendar such as the Thailand Tax Calendar 2026, and assign each to one firm.
- Step 2: Set a written cut-off date confirmed by both firms.
- Step 3: Collect the record set listed above.
- Step 4: Transfer e-Filing and Social Security Office access.
- Step 5: Reconcile opening balances against bank statements, VAT reports and withholding tax payable.
- Step 6: Check filing status with the Revenue Department, then run the first month-end close.
If payroll outsourcing in Thailand sits with the outgoing firm, payroll should move on the same cut-off so PND.1 and social security filings have one owner. Settlr Global's accounting and tax service typically completes handovers in 1 to 2 weeks, and its team works in Xero, Zoho Books or QuickBooks so the ledger can stay where it is. When comparing accounting services in Thailand, ask each provider to describe this sequence in writing and to confirm it covers record access, e-Filing setup and opening balance reconciliation.
What happens if a filing slips during the switch?
A missed return during a handover is treated the same as any other late filing. The costs generally build up in three parts:
- A late submission fine for the return itself
- A surcharge of 1.5% per month on the outstanding tax balance
Because the surcharge accrues monthly, the company should file and pay the overdue return as soon as it is found.
Frequently asked questions
How long does it take to switch accounting firms in Bangkok?
There is no statutory timeline. Settlr Global reports 1 to 2 weeks for a handover; the quality of the old records affects this.
Does a company need approval to change its accounting firm?
Neither the Revenue Department nor the DBD approves a change of accounting firm, but the new bookkeeper should notify the DBD through its e-Accountant system within 30 days of taking on the work, according to DBD guidance on bookkeeper notification (in Thai).55dbd.go.thdbd.go.th
5dbd.go.thdbd.go.th
Can the new firm file overdue returns from before the switch?
Once it has e-Filing access and the supporting records for that period, the new firm can file overdue returns.
Does changing accounting firm mean changing auditor?
Not necessarily. The auditor is a separate certified public accountant, generally appointed by shareholders at the AGM.
Should payroll move with the accounting firm?
Payroll often moves with the accounting firm, since PND.1 and social security filings depend on payroll data and are easier to manage under one owner.
About Settlr Global
Settlr Global is the operating arm of WOWS Global, a Singapore-incorporated corporate advisory and investment banking group, and provides a one-platform ecosystem for business operations in Thailand. It combines payroll, HR, legal, tax and incorporation support under a single team, so founders do not have to coordinate separate local agencies. The platform has processed payroll and compliance work for 200+ clients across 15+ countries, from early-stage startups to established multinational enterprises. Its Employer of Record service lets companies hire in Thailand in about two days, with or without a local entity.
If your company is planning to move its books to a new accounting firm in Bangkok, speak with the Settlr Global team about a handover plan built around your next filing dates.
References
- Revenue Department of Thailandrd.go.th
- Department of Business Development, Ministry of Commercedbd.go.th
- mol.go.thmol.go.th
- dbd.go.thdbd.go.th
- dbd.go.thdbd.go.th
