After registering a company in Thailand, organise your accounting before the first sale or supplier payment: appoint the person keeping the books, collect the company's records, agree approval responsibilities and test how a transaction reaches the accounts. Your first monthly close should produce reconciled balances, a list of unresolved items and a clear plan for the next period.
The 90 days in this guide are a practical planning horizon, not a legal grace period. A Thai limited company must begin keeping accounts from its registration date under section 9 of the DBD Accounting Act. An unopened bank account or a month without sales does not move that start date.
This guide focuses on a newly registered Thai limited company and its first accounting cycles. BOI promotion, overseas transactions, regulated activities or other entity types may need additional work from the outset.
A practical accounting calendar for your first 90 days
Use these phases to allocate work. Bring a task forward whenever a transaction, employee start date or applicable filing deadline requires it.
| Practical phase | Main work | Who coordinates it | Evidence that it is working |
|---|---|---|---|
| Registration and first week | Confirm the accounting period, company records, responsibilities and document storage. Plan the bank account and accounting system. | Company director and accountant | Setup record with named owners, first closing date and outstanding actions |
| First transactions and first month-end | Check invoicing, purchases, payment approvals and the tax treatment of actual activity. Reconcile the first period. | Operations team, payment approver and accountant | Transactions linked to documents; bank reconciliation; first reports and exceptions list |
| Following cycles, through day 90 | Resolve gaps, repeat the monthly close and adjust the workflow. Review upcoming obligations and cash needs. | Director or finance lead, with the accountant | Fewer unresolved items; reviewed reports; confirmed responsibilities for the next period |
Scroll this table sideways to see all columns.
There is no need to wait until day 90 for a report. Agree the first closing and reporting dates when the accounting work starts.
First week: establish the records and responsibilities
Confirm the accounting period and the person keeping the books
Record the registration date, first financial year-end and the person responsible for preparing the accounts. The Accounting Act requires the first accounts to be closed within twelve months of the accounting start date and requires a suitably qualified bookkeeper; see sections 10 and 19 of the DBD Act.
Agree a written scope for the initial setup and recurring work. Specify the document cut-off, reporting language, reports to be delivered and who prepares, approves, files and pays each applicable return. A company director and an external accountant need a shared timetable, even when the business has only a few transactions.
The first accounting period can be shorter than a full year. For example, the Revenue Department's PND51 FAQ, question 9, explains that a company with a first accounting period of less than twelve months does not have to file PND51 for that period. This exception does not remove other obligations. Have your accountant identify the filings that apply, using the actual period and business activity. Our Thai tax forms guide explains the different filing streams.
Create one company record and a document workflow
Keep the registration documents, company name, registered address, tax identification details, authorised signatories and any existing tax registrations together. Use those confirmed details when setting up customer and supplier records.
Decide where the team will store invoices, receipts, contracts and payment evidence. Each transaction should be traceable from the accounting entry to its supporting records. Agree who holds originals and how the accountant receives copies; a folder of photographs alone does not establish that every required document is complete.
Assign three responsibilities explicitly:
- Operations: supplies documents and explains what was bought, sold or agreed.
- Accountant: records the transactions, checks the treatment and raises unresolved questions.
- Company approver: confirms transactions and authorises payments and filings within the agreed scope.
In a small company, one person may perform several roles. Name that person for each step so an unanswered question does not become an assumed approval.
Plan the bank account and opening records
Confirm the bank's document requirements and authorised access with the bank. Arrange a way to obtain complete statements for every company account, including any payment platform used in the business. Keep payment approval separate from access granted for accounting work.
Retain evidence of capital paid, loans, deposits and initial purchases. Ask the accountant to reconcile the opening records with the registration and funding documents rather than entering a single unexplained starting balance.
If a founder has paid setup costs personally, keep the invoice or receipt, proof of payment, payment date, business purpose and proposed reimbursement together. Have the accountant assess how each item should be recorded and whether its tax documentation is adequate. A personal payment is not automatically sales revenue, and a receipt in a founder's name should not automatically be treated as a deductible company expense or input VAT.
First transactions: test the process before repeating it
Test the full document trail on a real transaction as soon as activity begins. Before then, you can check a sample document format without issuing a fictitious sale or filing a test return.
First customer invoice
Check the company and customer details, invoice numbering, description, dates, payment terms and VAT status. Agree how the team will record a credit note, refund or cancelled document so changes remain traceable.
Confirm VAT treatment before configuring the invoice. Company registration and VAT registration are different, and the answer depends on the actual business. Use our VAT registration guide for the threshold, preparation checklist and obligations after registration. Tell the accountant about overseas customers or mixed activities rather than assuming one template fits every sale.
First supplier payment
Match the contract or order, supplier invoice and payment instruction. Confirm the recipient and transaction type before deciding whether withholding tax applies. Make sure the person paying knows the approved amount and any deduction before releasing the transfer.
Our PND3 and PND53 guide explains the information needed for this decision. Keep the supplier payment evidence, any withholding certificate and the relevant filing evidence linked to the same transaction.
First employee or new system
If you hire staff, review employer setup, payroll inputs, approvals and applicable registrations before the first payroll cycle. Agree who gives the payroll team changes in pay or attendance and who authorises the final payment. YPN's payroll service describes the support available.
If you adopt software, test a sale, purchase, receipt and payment with the accountant. Check tax settings and opening balances before importing the rest of the records. YPN offers accounting software setup and training, including FlowAccount; the choice should suit your activity and document flow.
First monthly close: check what the reports actually contain
A bank balance alone will not explain unpaid invoices, supplier bills, founder funding or missing documents. Ask for the agreed reports and the reconciliation behind them.
Use this checklist at the first close and repeat it in the following cycles:
| Check | Question to resolve | Evidence to retain |
|---|---|---|
| Bank and payment platforms | Does each recorded balance reconcile to the statement? What remains unmatched? | Reconciliation and explanation of outstanding items |
| Sales and collections | Are invoices recorded once, and which amounts remain unpaid? | Sales records, receipts and receivables list |
| Purchases and payments | Are bills, advances and payments supported and assigned to the right period? | Supplier records, approvals and payables list |
| Founder funding and reimbursements | Are capital, loans and expenses separately identified? | Funding records and reviewed reimbursement schedule |
| Applicable filings | Who approves, files and pays, and what evidence confirms completion? | Confirmed timetable, approvals and submission/payment receipts |
| Reporting gaps | Which balances are still provisional, and who will resolve them? | Exceptions list with an owner and target date |
Scroll this table sideways to see all columns.
For each unresolved item, record the period, amount where known, missing evidence, responsible person and effect on reporting or filing. A report labelled final should not leave your team unaware of significant unresolved balances.
YPN's bookkeeping and reporting service covers transaction recording, reconciliation and financial reporting. Confirm the reports and timetable in your engagement; setup, catch-up work and annual work should each have a clear scope.
Through day 90: make the monthly routine repeatable
Review where the first close stalled. Did suppliers send incomplete documents? Were expenses approved after payment? Did an overseas office request a different reporting format? Fix the recurring cause and assign the change to someone who can implement it.
At each following close, review the bank position, customer collections, upcoming supplier payments and the costs of any planned hire or purchase. Ask how missing records affect the figures before using them to make a spending decision. Also review whether changes in activity create new registration or filing questions.
If the company has not made a sale, continue collecting records and reviewing its position. Capital movements, bank charges and setup costs can still require recording. Ask which returns apply to the company's registration status and transactions rather than treating “no revenue” as an instruction to do nothing.
By the end of this planning period, aim to have a working document trail, reviewed opening records, a repeatable close, understood reports and named owners for the next obligations. Any remaining gap should be visible, with a plan to resolve it.
Setting up the accounting for your new company?
YPN supports company registration and the accounting setup that follows. Tell us your registration date, business activity, first year-end, VAT status, expected transactions and whether you plan to hire. We can discuss the initial setup and recurring accounting scope with you.