Claude Code Uses Your API Key Over Your Subscription, Even When You’re Logged In

If you have both a Claude subscription (Pro/Max) and an ANTHROPIC_API_KEY environment variable set, Claude Code will use the API key and bill you at pay-as-you-go rates instead of using your subscription. This happens even when you're logged in, and it's documented behavior from Anthropic.

Subscription billing has fixed monthly costs and usage limits. API billing charges per token which can get expensive very quickly.

Authentication Priority

Claude Code prioritizes environment variable API keys over authenticated subscriptions. If ANTHROPIC_API_KEY is set, that's what gets used for billing.

How to Check What You're Using

In Claude Code, run:

/status

In your terminal, run:

echo $ANTHROPIC_API_KEY

If the second command returns a value, you're being billed via the API.

How to Fix It

Option 1: Remove the API Key Completely (Use Your Subscription)

If you want Claude Code to use your subscription, you need to remove the API key from your environment.

Step 1: Find where the API key is set

The API key is likely in one of these files:

• ~/.zshrc (if you use zsh, which is default on macOS)
• ~/.bashrc (if you use bash)
• ~/.bash_profile (older bash setup)
• ~/.profile (generic shell profile)

Open each file and look for a line like:

export ANTHROPIC_API_KEY=sk-ant-...

Step 2: Delete that line

Remove the entire export ANTHROPIC_API_KEY=... line from the file and save it.

Step 3: Clear it from your current terminal

The change won't take effect in your current terminal until you either restart it or run:

unset ANTHROPIC_API_KEY

Step 4: Verify it's gone

Run this to confirm:

echo $ANTHROPIC_API_KEY

It should print nothing.

Option 2: Keep the API Key for Other Scripts (Advanced)

If you need the API key for other scripts but want Claude Code to use your subscription, you need to keep them separate.

Step 1: Remove the API key from your main shell profile

Follow Steps 1-4 from Option 1 above to remove it from ~/.zshrc or ~/.bashrc.

Step 2: Create a separate file for API work

Create a new file called ~/.api_profile:

nano ~/.api_profile

Add this line:

export ANTHROPIC_API_KEY=sk-ant-your-key-here

Save and exit.

Step 3: Use it only when needed

When you need to run a script that uses the API, activate the API key in that terminal session:

source ~/.api_profile
./your-script.py

This sets the API key only for that terminal window. When you close it or open a new terminal, the API key won't be set, so Claude Code will use your subscription.

Set Spending Limits

If you do use an API key, configure spending limits in your Anthropic API settings to prevent unexpected charges.

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