Corporate Tax Planning [2026]: 5-Point Checklist to Cut Tax Before Year-End

What is corporate tax planning, and why start 4 months before year-end?

Corporate tax planning is the process of reviewing the structure of your accounting income and expenses against the conditions of the Revenue Code in advance, so that the business can use every tax benefit, expense deduction and allowance in full and 100% lawfully. The goal is to manage cash flow and reduce the cost of tax efficiently, not to evade tax or hide income.

The last 4 months of the year (September - December 2026) are the best time for tax planning, because the business has just filed P.N.D.51 (the half-year corporate income tax return) in August and so has actual figures for the first 6-8 months. Adding the actual figures to an estimate of income and expenses for the fourth quarter gives a realistic estimate of taxable net profit. If the profit looks high, the business still has time to budget for investment in assets, staff training, or clearing up missing expense documents before the accounting period closes on 31 December, rather than waiting until the year has ended, when accounting entries can no longer be adjusted.

A juristic person that qualifies as a small or medium enterprise (SME) under the definition of the Revenue Department must meet both of these conditions: 1) paid-up registered capital of no more than 5 million baht on the last day of the accounting period, and 2) income from the sale of goods and services of no more than 30 million baht in the accounting period. It then benefits from the stepped corporate income tax rates below.

Note: if either condition is not met (for example paid-up capital above 5 million baht or income above 30 million baht), the company is treated as an ordinary juristic person and pays a flat rate of 20% from the first baht of net profit.

5-point corporate tax planning checklist before year-end 2026

Preparing for the end of the 2026 accounting period should be done step by step through the following 5 checklist items.

1. Check the profit estimate against P.N.D.51 to avoid penalties and surcharges

Under Section 67 Ter of the Revenue Code, if a company's estimated net profit falls short of the actual net profit for the accounting period by more than 25% without reasonable cause, the business must pay a surcharge of 20% of the tax underpaid.

What to do:

• Take the trial balance at the end of August or September and add estimated income and expenses for the fourth quarter to calculate net profit for the full year
• Compare the new projected net profit with the estimated net profit filed on P.N.D.51
• If the difference exceeds 25%, file an additional P.N.D.51 promptly and pay the difference in advance before the end of the accounting period. The surcharge is then only 1.5% per month (or fraction of a month) of the additional tax payable, which avoids the full 20% surcharge

2. Review and screen non-deductible expenses under Section 65 Ter of the Revenue Code

Some accounting expenses cannot be treated as tax-deductible expenses and must be added back when calculating corporate income tax. Screening them during the last 4 months leaves time to fix the documents:

• Excess entertainment expenses (Section 65 Ter (4)): Ministerial Regulation No. 143 limits entertainment expenses to 0.3% of total income or paid-up registered capital (whichever base is higher), capped at 10 million baht. Gifts to customers must not exceed 2,000 baht per person per occasion. Food, drink and accommodation costs must be necessary under business custom. Total entertainment expenses must not exceed 0.3% of income or paid-up capital, and there must be receipts naming the person entertained, approved by an authorised person.
• Expenses with no evidence of the payee (Section 65 Ter (18)): cash payments supported only by an ordinary cash bill are not accepted as deductible by the Revenue Department. Fix this by preparing a "Payment Voucher" or a "certificate in lieu of a receipt", attaching proof of payment (an e-Payment transfer slip) and a copy of the payee's national ID card signed as a true copy.
• Non-creditable input tax: for example input tax on entertainment, or input tax on the purchase, hire or repair of passenger cars with no more than 10 seats. This cannot be credited against VAT, but it can be included in the cost of the asset for depreciation or recorded as a tax-deductible expense.

3. Use tax incentives and invest in assets before year-end

If the business has high accumulated net profit, it can use lawful tax measures to increase expenses and reduce tax as follows:

• 200% deduction for staff training: under Royal Decree No. 437, a business that sends staff to courses certified by the Ministry of Labour, or runs in-house training that meets the set criteria, can deduct the training costs (such as registration fees, trainer fees and accommodation) twice over (an extra 100% deduction).
• Investment in assets and initial depreciation (SME): if the business is an SME and buys machinery, equipment or computers before 31 December 2026, Royal Decrees No. 395 and 573 allow an initial depreciation deduction immediately on the date the asset is acquired. For example, 40% of the value of a computer can be deducted at once, with the rest spread over no more than 3 years. This brings a significant amount of expense into the 2026 accounting period.

4. Count inventory and deal with bad debts

A mismatch between physical stock and the goods and raw materials report creates serious tax risk, because stock missing from the report is treated by the Revenue Department as sold immediately and attracts VAT penalties and surcharges:

• Writing off damaged, deteriorated or expired goods: follow Revenue Department Order Por.79/2541 by appointing an inspection committee, keeping clear stock-count records and photographs of the destruction, and inviting a licensed auditor (CPA/TA) to observe the destruction. Only then can the loss be deducted for tax and no output VAT is due.
• Writing off bad debts: review overdue trade receivables under Ministerial Regulation No. 186. If the debt does not exceed 200,000 baht and there is reasonable written evidence of demands for payment that went unpaid, it can be written off as a bad debt for tax without going to court.

5. Plan high-season income and expenses (for service and tourism businesses)

For businesses in tourist areas, such as hotels, restaurants and cafes in Chiang Mai, the last 2 months of the year bring high sales. Accounting must strictly follow the accrual basis:

• Recognising advance deposits: deposits for rooms or catering received in November-December 2026 for stays or events in 2027 must be recorded as "advance receipts" (a liability), not as 2026 income, so that the current year's tax base is not overstated.
• Managing output tax at the counter: using a standard system such as a point-of-sale (POS) program (installed free when you use the monthly accounting service) helps issue abbreviated tax invoices, summarise daily sales in e-Tax form and deduct raw material stock automatically, reducing errors when sending sales data into the accounting system during busy periods.

Worked example: tax with and without corporate tax planning (Chiang Mai SME)

Here is a comparison of the tax outcome for Doi Sabai Cafe and Stay Co., Ltd., registered capital 2 million baht, total income for 2026 of 12,000,000 baht (qualifies as an SME):

Case 1: No advance tax planning (figures left to chance)

• Accounting net profit: 1,800,000 baht
• Expenses without receipts and excess entertainment expenses to be added back: 200,000 baht
• Taxable net profit: 2,000,000 baht
• Corporate income tax calculation:
  • First 300,000 baht of profit = exempt (0 baht)
  • Remaining profit of 1,700,000 baht (300,001 - 2,000,000 baht) x 15% = 255,000 baht
• Tax payable: 255,000 baht

Case 2: Tax planned 4 months before year-end 2026

• Accounting net profit before adjustments: 1,800,000 baht
• Expense documents completed, so there are no non-deductible expenses to add back (0 baht)
• Staff sent to service-standards training for 40,000 baht, eligible for the double deduction (an extra 40,000 baht deducted)
• Deteriorated raw materials and stock written off correctly under Por.79/2541: 60,000 baht
• Computers and a POS system worth 100,000 baht bought in September; the SME initial depreciation of 40% (40,000 baht) plus normal depreciation pro-rated over 4 months (6,667 baht) gives a total deduction of 46,667 baht
• Taxable net profit after planning: 1,800,000 - 40,000 - 60,000 - 46,667 = 1,653,333 baht
• Corporate income tax calculation:
  • First 300,000 baht of profit = exempt (0 baht)
  • Remaining profit of 1,353,333 baht (300,001 - 1,653,333 baht) x 15% = 203,000 baht
• Tax payable: 203,000 baht (an immediate, lawful tax saving of 52,000 baht)

Common tax planning mistakes, and why a Chiang Mai accounting firm helps

Tax mistakes that business owners often make, and that lead to back penalties, include:

• Waiting until March-April to gather documents: waiting until the accounting year has ended before sending documents to the accountant forfeits every tax planning opportunity, because assets cannot be bought, staff trained or bad debts written off retroactively.
• Using fake tax invoices: buying tax invoices with no real sale of goods is an offence under Section 90/4 of the Revenue Code, punishable by 3 months to 7 years in prison and a fine of 2,000 to 200,000 baht per invoice, plus a penalty of twice the tax and a surcharge of 1.5% per month.
• Neglecting withholding tax (WHT): payments for contract work or services (3%) or rent (5%) must have tax withheld and remitted on P.N.D.3 or P.N.D.53 by the 7th of the following month (or the 15th for online filing). Neglecting this makes the payer jointly liable for the tax plus a surcharge of 1.5% per month.

Working with specialists from a Chiang Mai accounting firm that operates through cloud systems and digital documents gives business owners accurate, up-to-date profit and loss figures in the fourth quarter, so tax can be calculated in advance precisely and tax matters handled online without travelling.

Frequently asked questions about corporate tax planning

1. The business has accumulated losses from earlier years. How can they reduce the 2026 tax?

Under Section 65 Ter (12) of the Revenue Code, a juristic person can carry forward net losses from up to 5 years before the current accounting period and deduct them in full from the 2026 taxable net profit. For example, if there was a net loss of 500,000 baht in 2024 and a net profit of 800,000 baht in 2026, the loss can be offset to leave a taxable profit base of only 300,000 baht (which is exempt under the SME rules).

2. If I buy office equipment or computers in December, how is depreciation calculated?

Depreciation on a purchased asset starts from the date the asset is actually ready for use, pro-rated by the number of days in that year; a full year cannot be claimed. For example, a computer ready for use on 16 December 2026 earns 16 days of depreciation in 2026. The exception is an SME, which can claim the 40% initial depreciation immediately on the date the asset is acquired under Royal Decree No. 395.

3. Can dividends paid to directors or shareholders be recorded as a company expense?

No. Dividends are a distribution of after-tax net profit to shareholders, not an operating expense incurred to generate income under Section 65 Ter (13). If they are recorded as an expense in the financial statements, they must be added back as a non-deductible expense when calculating corporate income tax.

4. Until when can a purchase tax invoice received late at year-end be used to claim input tax?

Under Section 82/3 of the Revenue Code, a full-form purchase tax invoice received late for a necessary reason can be entered in the input tax report and claimed within 6 months counted from the month after the month the tax invoice was issued. For example, a tax invoice dated 15 November 2026 can be used to claim input tax up to May 2027.

Summary: start corporate tax planning today for a stable business in 2026

Corporate tax planning 4 months before the end of the 2026 accounting period is a key strategy for controlling business costs. Checking the profit estimate against P.N.D.51, screening non-deductible expenses, using the double tax deduction and managing inventory correctly help the business cut its tax burden efficiently, avoid the risk of a back audit and keep the company's cash flow running smoothly.

If you are looking for a specialist in tax planning services and Chiang Mai accounting services, ready to be your business partner working on an online accounting system and digital documents, with a point-of-sale (POS) program worth 15,000 baht installed and taught free when you use the monthly accounting service, contact YMTD Accounting Partner in Chiang Mai to start planning your tax today.

Contact us for more information:
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