First-year tax and compliance actions for a new Thai company

01The first year goes wrong on rhythm, not on decisions

The tax and compliance traps a new operation hits in Thailand in its first year have one thing in common: by the time anyone notices, the penalty or the lost entitlement has already arrived, and arranging things in advance costs far less than repairing them afterwards. The most common ways it goes wrong:

• Carrying over an annual rhythm from home. Withholding tax (the PND series) and VAT (PP.30) are filed monthly, each with its own monthly deadline. Miss the monthly rhythm and the surcharge and penalties pile up month by month, then get settled in one lump when you catch up.
• Not registering for VAT when you had to. Once the statutory turnover threshold is reached, registration is compulsory, not an option. Sales made while unregistered are still taxable: the output tax has to be paid and penalties and surcharge run on it, while the input tax may not be recoverable to the same extent. One side gets settled and the other does not, and in cash terms that is a net outflow.
• Buying during the pre-operating period before registering. No registration means no input tax credit, and the tax paid on those purchases is pure cost. Large equipment and raw material purchases very often fall exactly in that window.
• Handling only one of the two cross-border obligations. When you pay a service fee or a royalty overseas, withholding the income tax and filing it, and self-accounting the VAT on the overseas service, are two separate obligations on different returns. Miss either one and the back tax and the penalty land on the Thai company.
• Letting supplier invoices pile up unchecked. Input tax credit and refunds are given on a proper Tax Invoice carrying the particulars the law requires; an ordinary receipt does not count. Leave the checking until you apply for a refund or the Revenue Department comes in, and they get struck out all at once, with the input tax gone.
• Capital contributions and nominee arrangements are buried on registration day. The DBD contribution-verification rule that took effect on 2026-01-01 (Order 2/2568) requires Thai shareholders in a company with foreign participation to submit bank statements for the 3 months before they subscribe for the shares. Nominee arrangements also draw enforcement under the anti-money-laundering law: assets can be frozen without a court order and the company can be forced into dissolution. Across 2025-2026, 852 companies have been prosecuted, and BOI promoted status is no exemption.

None of these is difficult taken alone. The difficulty is that the first year is when you have the fewest people and the most items running at once, and every miss costs real money. So this is not written to be read. It is a working sheet you can tick off, cut down and hand out.

02What the three sheets cover

Three sheets.

• The first-year action sheet counts from the month registration completes as month 0 and runs through to the first annual filing period. Every row states the action, the basis and the points that matter, what triggers it, and what follows from missing it; the last two columns are left for the person responsible and the completion date, so rows get cleared one at a time.
• The one-off and recurring obligations sheet sorts each action into the ones you do once and are finished with, and the ones that come round every month or every year, setting out for each what follows from missing it, what makes it hard to repair, and which records to pull together for the advisory team to check.
• The internal-rules countdown sheet takes the few internal rules that should be standing by the end of the first year — a filing calendar for the whole year, checking supplier tax invoices in the month they arrive, deciding a cross-border payment before making it — and brings each one down to an internal data due date, a person responsible, a reviewer, and the date it was last checked.

Every cell that changes with the individual case is left blank and shaded amber: the threshold amount, the deadline for each return, your own owners and completion dates, whether a given row applies to your company at all. Those are for the advisory team to settle against business type, turnover basis and registration status, or for you to fill in yourself. General rules are written into the cells and are not shaded — amber means this one is not settled yet. The sheet is a working paper for the advisory team and the client to fill in together, not a ready-made answer: write a fixed number in and it gets treated as a settled conclusion.

03Two kinds of miss: fixed once, or made up every month

Not every first-year action sits on the same plane. Some are one-off: done is done, but very hard to go back for once the moment has passed. Documenting the capital contribution at registration is the clearest case — bank statements for the 3 months before the Thai shareholders subscribe for their shares cannot be produced after the fact.

Others are recurring obligations, where one miss becomes a burden in every month that follows. Completing VAT registration puts the company into the monthly filing cycle, and a month with no transactions still has to be filed as a nil return; not filing it counts as late all the same. This is easiest to lose sight of in the pre-operating period or a slow season — there is little business, the finance side feels there is nothing to report, a few months lapse, and from then on it is catching up on old periods and filing the current one at the same time. Historical gaps in particular should not be patched piecemeal: which periods, in what order, how the surcharge is worked out — plan the whole thing before touching any of it, because patching one period and missing the next only leaves breaks.

A third kind recurs in the timing: the invoice date, the payment date and the tax month a return belongs to all have to line up. When the tax point arises follows clear rules and does not necessarily match the date you are paid. If they do not line up, your output tax month and your customer's input tax month fall out of step, the cross-check shows a mismatch, and that invites an inquiry.

04How to work through the sheet

Four steps. First, cut the rows that do not apply to you — no cross-border payments, no employees yet, not a BOI-promoted company: delete those rows, and what is left is your sheet. Second, collect the amber cells into a single list of questions and give it to the advisory team to settle in one pass, above all the registration threshold and the deadline for each return; settle those once and every other row can land. Do not guess at them. Third, take each recurring obligation's deadline, move it earlier into an internal data due date, and split collecting the data from filing the return. Fourth, at the start of each month look back at the last one: was everything done, and has a new cross-border payment or a new employee appeared that needs another line added.

There are three situations you should not judge for yourself: turnover approaching the threshold with no certainty about which basis to count on; large purchases already made in the pre-operating period, with the input tax treatment still open; and a suspicion that some past period should have been registered and was not. The third especially needs a plan for the whole thing before anything is filed. Whether your company has passed the threshold, when it should have registered, how pre-operating input tax is treated and whether there is a historical gap all have to be checked item by item against turnover records, business type and purchase records. What the sheet asks of you is to get those records together for the advisory team — not to measure yourself against a threshold it deliberately does not print.