Why
Author order alone doesn’t say who did what. A CRediT statement makes each person’s contribution explicit and auditable, gives credit for work that byline position hides (data curation, software, supervision…), and is increasingly required by journals and funders.
Who
Usually drafted by the corresponding author, but it should reflect everyone’s view of their own contribution — not just one person’s assumption. Every co-author should see and agree with the final statement.
What
Each of the 14 standardised CRediT roles (Conceptualization, Investigation, Writing, Supervision, and so on) is assigned to whoever did that work, with an optional Lead / Equal / Supporting degree where it helps.
How
Add every author below, tick the roles they contributed, review the generated statement, then copy or export it for your submission system.
When & where
As soon as you plan the paper — not at submission time. Fill this in early, then share the exported statement with every co-author over Slack or email straight away. Agreeing on contributions up front, in writing, heads off disputes later: it effectively works as an authorship contract for the project.