Throughout the past early year, we have increasingly seen posts and questions about "taxes" on social media in forms like these:
- "I owe 1 million baht in back taxes, paid 500,000 in the first installment. How many installments can I pay?"
- "Selling online with 200 million baht revenue, but only reported 30 million. What to do if audited retroactively?"
- "I opened a nail salon. Where do I start filing taxes?"
This is a clear warning sign that "being outside the tax system" is becoming more difficult, because more peers are being audited—not by coincidence, but due to the Revenue Department's serious use of AI and Big Data to rigorously link financial transactions (e-Payment) information.
For beginners, sellers, or freelancers who want to "do things correctly" to avoid future impacts and build a sustainable business, Thairath Money invites you to explore a 5-step roadmap that turns the complex tax issue into something manageable.
Step 0: Being outside the tax system is a “structural risk.”
Many mistakenly think not filing taxes saves costs, but in reality, it is riskier than expected.
- Retroactive audits up to 10 years: If you never filed a return, the Revenue Department can audit back a decade or more.
- The frightening power of interest: You must pay an additional 1.5% per month (18% annually) plus penalties of 1-2 times the tax amount. Tax debt can easily grow to nearly five times the original amount.
- The invisible barrier: Without tax filing documents (P.N.D. 90/91), banks often reject loan applications for home, car, or business due to lack of credible income proof.
- Risks of criminal and cyber cases: In an era of rampant fraud, using "tax avoidance techniques" (such as using others’ accounts to receive money) may unintentionally expose you to serious criminal charges like money laundering or mule accounts, which carry much harsher penalties than tax cases.
- Disqualification from government benefits and measures: The digital government uses tax data screening to allocate benefits. Those outside the system face huge "opportunity costs," such as missing out on stimulus programs like Easy E-Receipt.
Step 1: Know the 8 types of taxable income under the law.
Before filing taxes, you must know which category your income falls into according to law (Section 40) to deduct expenses correctly. The Revenue Department classifies income into 8 types as follows:
- Type 1 [40(1)] – Income from employment: Basic income of permanent employees, such as salary, bonuses, allowances, pensions, or even employer-paid tax.
- Type 2 [40(2)] – Income from duties or positions: For occasional jobs, such as commissions, fees, meeting allowances, or freelancers paid per job.
- Type 3 [40(3)] – Income from copyrights and intellectual property: Including goodwill, patents, or annuities from wills and court judgments.
- Type 4 [40(4)] – Income from interest and dividends: Includes profit shares, benefits from stock transfers, and importantly, "benefits from cryptocurrency or digital tokens" are also classified here.
- Type 5 [40(5)] – Income from leasing assets: Such as rent from houses, land, cars, including income from lease-purchase or installment sales breaches.
- Type 6 [40(6)] – Income from independent professions: Specifically defined by law, including medicine, law, engineering, architecture, accounting, and fine arts.
- Type 7 [40(7)] – Income from contracting: The key is the contractor must "invest in procuring major supplies" beyond tools, e.g., construction contractors who provide materials.
- Type 8 [40(8)] – Other income: All income not in the first seven categories, such as online sales, commercial business, agriculture, transport, or real estate sales.
Income must be separated because each type has different tax deduction advantages; some allow high flat-rate deductions, others require actual expenses only. Choosing the wrong type can cost benefits or draw unwanted Revenue Department attention.
Step 2: The "1.8 million baht test" – Why register VAT?
For sellers, the figure 1.8 million baht per year is a "deadline" to know. If revenue exceeds this, VAT registration is required within 30 days from the date income surpasses the threshold.
Failure to comply risks paying 7% VAT retroactively from the date exceeding the threshold plus double penalties and 1.5% monthly interest.
Why should you register VAT correctly?
- Input Tax Credit: You can deduct the 7% VAT paid on purchases from the VAT collected from customers, reducing costs immediately.
- Establish a standard accounting system: VAT registration requires monthly purchase-sales tax reports, helping you see your true cash flow.
- Business gateway: Large companies or malls only accept VAT-registered partners.
- Credibility: VAT registration is strong evidence when applying for loans and shows business transparency.
Step 3: Tax deduction planning (Tax Shield).
Tax Shield means using legal rights to reduce "net income" before tax calculation, helping pay less tax or get bigger refunds. There are 4 main groups:
1. Family group (basic rights)
- Personal exemption: 60,000 baht (automatic for everyone).
- Spouse exemption: 60,000 baht (if spouse has no income).
- Children: 30,000 baht each (the second child onwards born from 2018 gets 60,000 baht).
- Supporting parents/disabled persons: 30,000 baht per parent, 60,000 baht per disabled person.
2. Savings and insurance group, such as
- Life/health insurance: Life insurance up to 100,000 baht, health insurance up to 25,000 baht (combined max 100,000 baht).
- Tax-saving funds like RMF: Up to 30% of income (max 500,000 baht), Thai ESG funds: Up to 30% of income (max 300,000 baht).
3. Government and real estate measures, such as
- Home loan interest: Deduct actual paid interest up to 100,000 baht.
- Tax deduction for solar rooftop installation up to 200,000 baht (2026 - 2028).
- General donations: Deduct actual amount up to 10% of net income.
- Special donations (double deduction): Such as to schools or public hospitals via e-Donation system, deductible twice the actual amount.
Note: Remember to update special tax deduction rights each year.
Planning tip: Use formula Net Income = Assessable Income - Expenses - Deductions.
For online sellers, check "actual costs"; if over 60%, choosing to deduct actual expenses (instead of flat rate) can create a significant Tax Shield.
Also, use health insurance benefits as protection; beyond 25,000 baht tax reduction, it guards against future medical costs. Consider DCA investment planning early in the year to manage cash flow better.
Step 4: How to handle a back tax audit.
If you receive a letter or summons from the Revenue Department, proceed as follows:
- Stay calm and check the document type: Is it a "meeting invitation" to request more information or a "tax audit summons" (per Section 19)? Also confirm which tax year is under audit.
- Prepare evidence: Collect past account statements, withholding tax certificates (Form 50), tax invoices (if any), and recorded income-expense accounts.
- Attend the official appointment: Meeting in person shows good faith and can shorten the audit. Answer truthfully and provide documents verifying income sources.
- Negotiate penalty reduction: While interest (1.5% per month) cannot be reduced, you may request reduction or waiver of penalties (1-2 times the tax) if you prove no intention to evade and cooperate well.
- Use installment payment rights: If tax owed is 3,000 baht or more, you can request up to 3 installments with no interest.
- Appeal rights: If you disagree with the tax assessment, you can appeal within 30 days from receiving the assessment notice.
Step 5: Maintaining tax system status.
The final step in tax management is "tax compliance," the most valuable risk prevention strategy. A good tax record becomes a "shield" for assets and a "gateway" for long-term financial matters, with these key practices:
1. Discipline in filing "every year" even if income is below the threshold.
Filing income tax returns (P.N.D. 90/91) even if no tax is due shows good faith and builds "transparency history" in government databases.
Additionally, by 2027, the government plans to implement Negative Income Tax, allocating benefits based on tax filing data, so being in the system secures future rights.
2. Keep documents for at least 5 years.
The key to audit readiness is "evidence." Keep these documents for at least 5 years (10 for maximum safety):
- Income evidence: Withholding tax certificates (Form 50), receipts, or employment contracts.
- Expense evidence: If deducting actual expenses, keep tax invoices or receipts clearly showing payee names.
- Bank statements: Keep bank account records matching declared income.
3. Use digital tools to verify accuracy (D-MyTax).
Today, you don't have to remember all data yourself. The Revenue Department offers "My Tax Account" and "D-MyTax" systems linking automatic deductions such as life insurance, donations (e-Donation), and fund purchases. Regularly checking via RD Smart Tax app helps file correctly and reduces risk of errors leading to audits.
4. File taxes on schedule (Timeline).
Maintaining good status means avoiding late filings to prevent hard-to-reduce penalties:
- Half-year tax (P.N.D. 94): For income types 5-8, file between July and September each year.
- Annual tax (P.N.D. 90/91): File online from early year until early April annually.
- Consequence of delay: You must pay "additional tax" at 1.5% per month of tax due, which generally cannot be reduced unlike penalties.
5. Plan distributed deductions (DCA).
To maintain financial stability alongside taxes, use dollar-cost averaging by gradually investing in RMF or Thai ESG funds instead of lump sums late in the year. This improves cash flow management and reduces risk from price fluctuations.
Summary formula to check your status.
Regularly estimate figures to plan ahead using the formula:
Net Income = Assessable Income - Expenses - Deductions.
Making tax management a "normal" part of daily life helps your business and finances grow sustainably with correctness and without worry about retroactive audits.
Source: Revenue Department, itax, ttb, Thai Financial Planners Association.
