deduction amount; amount deducted; abatement
Used in tax, accounting, and financial contexts for the sum subtracted from a total, such as taxable income or a payment.
今年の所得税の控除額は昨年より増えた。
The income tax deduction amount this year increased compared to last year.
Calculate the deduction amount for medical expenses.
免除額 is an exemption amount (often from obligations), whereas 控除額 is a deduction from a calculated total.
Compound of 控除 (deduction) and 額 (amount). The exact historical derivation is uncertain, but the meaning is transparent from its components.