What taxes does a Thai company file each year, and when are they due?

01The monthly cycle: two waves every month

A lot of Chinese owners picture Thai tax filing as something you do once a year. That is the most expensive misunderstanding on the list. A company that is trading normally has two waves of filings every month, on top of a half-year prepayment and an annual return. Miss any one slot and the penalty and surcharge start rolling up month by month.

• Early in the month (on paper, usually the 7th of the following month): the withholding series — PND.1 (withholding on employee salaries; if you pay wages, you file), PND.3 (service fees and commissions paid to a Thai individual), PND.53 (rent and service fees paid to a Thai juristic person), plus the two cross-border forms PP.36 and PND.54, covered in the next section.
• Mid-month (on paper, usually the 15th of the following month): PP.30, the VAT return, filed every month once you are VAT-registered, and the social security contribution, employer and employee portions.

Three things to get right. The period covered is always last month's business, with the deadline falling in the month after. PND.1, PP.30 and the social security filing are compulsory returns: if there was no activity that month, you still file a nil return, and not filing counts as late all the same. Electronic filing (e-Filing) usually carries a few extra days, but how many days is set by the Revenue Department (RD) announcement in force each period — do not treat it as a fixed entitlement.

One practical detail: payroll filings follow the month of payment. May salaries actually paid in June belong to the June payment period and go in with the batch filed early in July. Companies whose payday crosses a month boundary get this wrong more often than anything else.

02The two cross-border forms Chinese-invested companies most often miss

Paying money out of Thailand — service fees, royalties, software subscriptions — triggers two separate obligations at once. PND.54 is the withholding return on the outbound payment (section 70 of the Revenue Code); whether you withhold, and on what basis, depends on how the income is characterised and on the applicable tax treaty. PP.36 is reverse-charge VAT (section 83/6): the overseas supplier will not collect Thai VAT for you, so as the buyer you declare and pay the 7% yourself, then claim it back as input VAT on the PP.30 for the tax month the receipt belongs to. The net cost is close to zero, but the surcharge and the audit record from failing to file are real.

PND.54 is the cross-border form whether the recipient is a company or an individual. PND.3 is the domestic form, for payments to a Thai individual. What decides which one you are in is the recipient's tax residence — not nationality, not where they happen to be — and residence has to be settled case by case. See what to withhold on payments to overseas suppliers.

• One form per payee. PP.36 is filed payee by payee. Three overseas suppliers paid in the same month means three forms; they cannot be combined.
• Paying on a personal card does not exempt you. When the owner puts the company's overseas software subscription on a personal card, the company is still the party using the service and still the party that has to file. In practice this is the single most common source of missed filings.

03Half-year and full-year: PND.51 and PND.50

PND.51, the half-year corporate income tax prepayment, is filed within two months after the end of the first half of the accounting year — usually around the end of August, with the official date governing. You need the first-half profit and loss and a full-year profit estimate, and you pay part of the tax up front; the Revenue Department (RD)'s own basis of calculation governs.

PND.50, the annual return, is filed within 150 days after the accounting year end — for a company with a 31 December year end, around the end of May the following year. It must be accompanied by audited financial statements, and what you already paid on PND.51 is credited against it.

The same annual chain has two more links. The shareholders' meeting (AGM) to approve the accounts must be held within 4 months of the year end, and the annual financial statements must be filed with the Department of Business Development (DBD) within 1 month of the AGM. One set of audited accounts feeds both the Revenue Department (RD) and the DBD, so book the auditor's slot well ahead.

04What being late actually costs, and three ways it goes wrong

Filing late produces a penalty plus a surcharge — the surcharge generally accrues monthly, at about 1.5% per month, per the Revenue Department (RD)'s rules in force. And because the cycle repeats every month, one missed month usually turns into fighting on two fronts from then on, catching up the old period while filing the new one, with the gap widening the longer it runs.

• Mismatched tax months draw scrutiny. If the month you declare output VAT does not line up with the month your customer claims the input, the Revenue Department (RD)'s input-output matching will show a discrepancy. Invoice date, payment date and filing date need to be aligned.
• "No transactions" is not the same as "nothing to file." A compulsory return with nothing in it is still filed as a nil return; skipping it counts as late.
• Catch-up filings should be worked out in one go. When you find that historical periods were missed, which periods to correct, in what order, and how the surcharge is computed should be planned as a whole. Fixing one period and skipping the next just leaves fresh gaps.

The dates on this page are the general deadlines for paper filing. e-Filing carries an extension and public holidays push dates back; the Revenue Department (RD)'s current announcement governs for each period.

05Your own calendar is not the generic one

No two companies have the same filing calendar. Whether you have employees, whether you are VAT-registered, whether you pay anything out of Thailand, and when your accounting year ends together decide how many lines are on your calendar, which returns are compulsory, and which you can properly leave unfiled.

The complete deadline table for a specific company, and any historical gaps that need clearing, have to be checked by our advisers item by item against your registration status, your books and your contracts. Copying a generic list is not a substitute. Related: the tax traps of the first year in Thailand and what a tax health check turns up.