一いち時じ所しょ得とく

noun

occasional income; temporary income

Primarily used in Japanese tax law to refer to income that is not regular, such as winnings, prizes, or one-time gains. In everyday conversation, it may be used loosely for any irregular earnings.

• 懸けん賞しょうで当あてた賞しょう金きんは一いち時じ所しょ得とくとして課か税ぜいされる。

  Prize money won in a contest is taxed as occasional income.

• 副ふく業ぎょうの収しゅう入にゅうが一いち時じ所しょ得とくにあたるかどうか税ぜい理り士しに相そう談だんした。

  I consulted a tax accountant about whether my side-job income qualifies as occasional income.