TOOL / H-US-02How the clock works
The threshold is more than 12 months, and the holding period is conventionally counted from the day after acquisition. In practice: a lot acquired on 10 March is long-term for disposals on or after 11 March of the following year. The tool applies exactly that convention — and the convention itself is one of the items on this page's verification list, which is why the working badge stays until a reviewer signs it.
Three details the tool cannot know about your lot: transferred lots keep their original clock only if you can prove the original acquisition date — the broker's "date first seen" is not your date (see the 1099-DA page); income-event lots (staking, airdrops) start their clock at receipt, at the value recorded then; and which lot you dispose of is a specific-identification question decided at or before the sale, not after.
This tool illustrates one rule with the convention stated above. It is not advice on any disposal, and reading it creates no professional relationship.