“固定收入”常见的英文表达是 “fixed income”。
例如：
He has a fixed income every month, which allows him to live a stable life.（他每个月有固定收入，这让他能过上稳定的生活。）
Many retirees rely on their fixed incomes to cover daily expenses.（许多退休人员依靠他们的固定收入来支付日常开销。 ）