noun
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.
医療費控除の控除額を計算する。
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.