tax-free ratio; tax-free percentage
Used in economic, accounting, or tax contexts to refer to the proportion of income, goods, or transactions that are exempt from taxation.
The tax-free ratio for this product is 8%.
At duty-free shops, the tax-free percentage may vary depending on the purchase amount.
Compound of 免税 (tax exemption) + 率 (rate, ratio). The derivation is straightforward from its components.