Taxpayers who have paid income tax on earnings sourced from mainland China may claim a deduction under specific regulations. The deduction is allowed only when the foreign tax has been paid on income that is subject to Taiwanese taxation, and the taxpayer must provide proof of payment, such as tax receipts or official statements from the relevant Chinese tax authority. The amount deductible is limited to the portion of foreign tax that exceeds the tax payable on the same income in Taiwan, preventing double taxation. Documentation must include the tax return filed in China, evidence of withholding, and a calculation showing the comparative tax liability. The application is submitted together with the annual income tax return, and the tax authority reviews the claim to confirm eligibility. Properly navigating these requirements can significantly reduce the overall tax burden for businesses and individuals engaging in cross‑border economic activities.