控除
こうじょ · koujo · JLPT N1 · noun
deduction
🧾 控除 = 控 hold back + 除 remove: an amount held back and taken off what you owe
The subsidy sense works the same way: 控 holds a share back and 除 removes it from the total, so the payment or reduction comes off the amount owed.
除 — left ear/mound 阝 + surplus 余
除 combines the 'mound/steps' radical 阝 (originally 阜, a hill) with 余 as the phonetic. It first meant the steps of a palace, then extended to 'remove' or 'clear away' (as one sweeps steps clean), and later to mathematical 'divide.'