noun
off the books; unaccounted
Used in accounting and finance to describe assets, liabilities, or transactions not recorded in official ledgers. Often implies hidden or unofficial handling.
その会社は簿外債務を抱えていることが発覚した。
It was discovered that the company had off-the-books debts.
簿外取引は会計監査で問題になる。
Off-the-books transactions become an issue in accounting audits.