ANTHROPIC_API_KEY in Claude Code: Avoid Surprise API Charges

1 day ago

2 min read

⚡ TL;DR If ANTHROPIC_API_KEY is set, Claude Code uses it instead of your subscription, billing pay-as-you-go. Check with /status and remove it with unset or from your shell config.

Paying for a subscription but seeing API charges? An ANTHROPIC_API_KEY variable is the usual cause.

Fix guide. 🔑

🔑 Why ANTHROPIC_API_KEY Matters

Claude Code prioritizes environment variable API keys over subscription logins, so usage bills to that key's API account.

🔍 How to Check

Run /status in Claude Code to see the active authentication, or echo $ANTHROPIC_API_KEY in a terminal outside Claude Code.

🧹 How to Remove It

Options:

⏱️ unset ANTHROPIC_API_KEY for the current session
📝 Delete the export line from your shell config to remove it permanently
🪟 On Windows, delete it from System Environment Variables

💡 Pro tip Use a separate shell profile for API work so the key never leaks into subscription sessions.

✅ Confirm

Restart your terminal and run /status again to confirm the subscription login is active.

One environment variable can change your bill. Need a Claude Code billing audit? Lord Of The Wix can check it. ✨

❓ ANTHROPIC_API_KEY FAQ

Why am I charged API fees with a subscription?

An ANTHROPIC_API_KEY variable overrides your login.

How do I check which auth is active?

Run /status in Claude Code.

How do I remove the key for now?

Run unset ANTHROPIC_API_KEY.

How do I remove it permanently?

Delete the export line from your shell config.

What about Windows?

Delete it from System Environment Variables.

🙏 Credit: This article is based on public information from the Claude Help Center. Claude is a product of Anthropic. Source: support.claude.com.

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