Short answer: yes to both, and there is no numeric cap either way. A single author can be assigned as many of the 14 CRediT roles as actually apply to what they did, and a single role can be assigned to as many co-authors as actually performed that work. The taxonomy is built around describing real contributions accurately, not around distributing a fixed set of labels one-per-person.
What the official CRediT documentation says
CRediT (the Contributor Roles Taxonomy, formalized as ANSI/NISO Z39.104-2022 and jointly stewarded by CASRAI and NISO) is maintained at credit.niso.org, the authoritative source for how the taxonomy is meant to be applied. Its implementation guidance states the two mechanics this page is about directly:
- Multiple roles per contributor: “Individuals can have several roles – it is common that researchers will have made several contributions to a research output.”
- One role, multiple contributors: “The same role can be assigned to multiple individuals – a specific CRediT role can also be assigned to multiple individuals.”
Neither statement is qualified with a maximum. The taxonomy’s own framing is that each research output is different, and only the roles that genuinely describe what happened should be used — there is no requirement to fill every role, no requirement to spread roles evenly across authors, and no rule limiting how many roles one person can hold or how many people can hold one role.
The degree-of-contribution qualifier, for when a role is shared
When two or more authors share a role, CRediT includes an optional refinement built into the ANSI/NISO standard itself: a degree-of-contribution qualifier of lead, equal, or supporting, attached to that role for that person. This isn’t a separate mechanism bolted on by publishers — it’s part of the taxonomy, meant specifically for the shared-role case, so that “three authors did Data Curation” can optionally be refined to who led it and who supported it, without inventing a 15th role or splitting the task into artificial sub-categories. Qualifiers are optional; a shared role with no qualifier simply means all listed contributors performed it without a stated hierarchy. See CRediT Author Statement Samples for worked examples using lead/equal/supporting in context, and the JATS XML encoding guide for how the qualifier is marked up (a specific-use attribute on the <role> element).
How this looks in a real author contribution statement
Using CASRAI’s standard placeholder roster (not a real publication):
Author Contributions
Zhang San: Conceptualization, Methodology, Writing – original draft.
Priya Patel: Data curation (lead), Formal analysis.
Erin Wright: Data curation (supporting), Investigation.
Adam Lloyd: Supervision, Writing – review & editing.
Two mechanics are visible in that one statement: Zhang San holds three roles at once (multi-role-per-author), and Data curation is shared between Priya Patel and Erin Wright with a lead/supporting split (multi-author-per-role). Both are ordinary, unremarkable CRediT usage — not edge cases requiring special justification.
How this works during manuscript submission
Corresponding authors don’t type free-text role lists into most systems. Publishers that collect CRediT — Elsevier via Editorial Manager, and comparable role-selection interfaces at PLOS, Wiley, Springer Nature, and Taylor & Francis — present the 14 roles as a checklist per co-author: the corresponding author ticks one or more roles for each name on the byline. Because it’s a checklist rather than a forced single-select, holding several roles or sharing one role with a colleague requires no special handling in the submission form itself; it’s simply multiple checkboxes ticked for the same person, or the same checkbox ticked for several people. The rendered statement in the published article reflects whatever combination was selected. See CASRAI’s submission-system playbooks for platform-specific mechanics.
Common questions this raises
Is there a limit on how many roles one author can have?
No fixed limit is set by the taxonomy. In practice, most individual statements list one to three roles per author, simply because that reflects what most contributors actually did — but that’s a description of typical usage, not a rule. A sole author correctly credited with all 14 roles they personally performed (common on single-author papers) is not a misuse of the taxonomy.
Does holding more roles mean an author contributed “more,” or carries more authorship weight?
No. CRediT is a contribution-disclosure taxonomy, not a weighting or scoring system, and it is explicitly not a test of who qualifies as an author. Authorship eligibility is governed separately — typically by criteria like the ICMJE authorship criteria (substantial contribution, drafting or revising, final approval, and accountability) or a journal’s own policy. A CRediT statement records what each already-qualified author did; it does not determine byline order, seniority, or who counts as an author in the first place. See CRediT vs ICMJE: what’s the difference for the fuller comparison.
If several authors share a role, do we have to specify each person’s exact extent of involvement?
No, it’s optional. The lead/equal/supporting qualifier exists for when that distinction is genuinely informative, not as a mandatory disclosure. Many published statements list a shared role with no qualifier at all, which is a complete and valid statement meaning all listed authors performed that role without a stated hierarchy between them.
Do CRediT roles need to be mutually exclusive — i.e., does assigning Data Curation to one author rule it out for another?
No. Roles are not a fixed pool divided among authors like a headcount allocation. Multiple authors performing genuinely the same kind of work should all be credited with that role; the taxonomy is describing reality, not rationing categories.
Can the same author be listed with a role qualifier that conflicts with another author’s qualifier for the same role?
Qualifiers describe each person’s degree of contribution to that specific role, so it’s normal and expected for them to differ — one author “lead,” another “supporting,” on the same role, in the same statement. What matters is that the qualifiers accurately reflect the actual division of work, not that they match.
The core principle
CRediT roles are assigned based on what was actually done, not distributed to satisfy a quota or avoid overlap. A contribution that spans several roles gets several roles; work performed jointly by several people gets that role attached to each of them, optionally refined with lead/equal/supporting. For the underlying definitions of each role, see CASRAI’s CRediT overview and the individual role pages; for how CRediT relates to authorship qualification more broadly, see the CRediT & Authorship pillar.
