Prepare inputs for a Thai income-tax estimate
Separate income, expenses, allowances and withholding before estimating tax.
Identify income types first
Expense deductions differ by income type. The main calculator supports employment income within its scope; the multi-income tool is limited to sections 40(1) and 40(2).
Separate allowances and withholding
Allowances reduce net taxable income. Withholding is a credit against calculated tax. Entering one as the other distorts the balance.
Check the tax year and exclusions
Use the rates and ceilings for the year shown by the tool and confirm actual eligibility in Revenue Department material. The result is not a filed return.
Sources and scope
This guide explains how to prepare inputs within the tool's scope. It is not legal, tax, financial or academic advice.
Content and sources checked 18 September 2026