A subsequent event is the US GAAP term for a post-balance-sheet event: a significant event or transaction that takes place after the balance sheet date but before the financial statements are issued or available to be issued. The main entry explains the two types of event, the evaluation period and a worked example.
Same idea, different wording
Under generally accepted accounting principles (GAAP) in the United States, subsequent events are covered by ASC 855 and are divided into recognised and nonrecognised events, sometimes called Type I and Type II. Under IFRS, IAS 10 uses the wording "events after the reporting period" and calls the two types adjusting and non-adjusting. The general phrase post-balance-sheet event is common in UK and older usage.
A recognised subsequent event gives more evidence about a condition that already existed at year end, such as a customer's bankruptcy confirming that a year-end receivable was uncollectible, and the figures are adjusted. A nonrecognised event reflects a new condition, such as a fire after year end or a new borrowing, and is disclosed in the notes rather than adjusted for if it is material.
Auditors also use the term for their own review of events up to the date of their report. If events after year end cast doubt on whether the company can continue operating, the going concern assumption must be reconsidered.