CLAUDE_CODE_ATTRIBUTION_HEADER

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_ATTRIBUTION_HEADER is a Claude Code environment variable: API billing header in system prompt. Present since v2.1.69 or earlier and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Present since v2.1.69 or earlier
Category	Other
Official docs	Listed

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_ATTRIBUTION_HEADER=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_ATTRIBUTION_HEADER": "<value>"
  }
}

Release notes that mention it

Related variables

CLAUDE_CODE_ATTRIBUTION_ANNOUNCEMENT
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID
ANTHROPIC_WORKSPACE_ID
BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.
CLAUDE_AFK_COUNTDOWN_MS

Frequently asked questions

What does CLAUDE_CODE_ATTRIBUTION_HEADER do?

API billing header in system prompt

Which Claude Code version has CLAUDE_CODE_ATTRIBUTION_HEADER?

Present since v2.1.69 or earlier and still present in v2.1.294.

How do I set CLAUDE_CODE_ATTRIBUTION_HEADER?

Export it before starting Claude Code (export CLAUDE_CODE_ATTRIBUTION_HEADER=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.