The Problem

If you use multiple GitHub accounts—for example, a work account and a personal account—you may encounter a frustrating issue when working from the command line:

You try to push code to your personal repository, but GitHub rejects it with a permission denied error because it is authenticating as your work account.

This happens even though you are the owner of the personal repository.

Why This Happens

  • GitHub allows multiple accounts, but Git does not automatically switch identities per repository
  • The CLI (SSH or HTTPS) reuses a cached or default identity
  • As a result, all pushes to github.com may be attempted using the same account

The Solution: Separate SSH Keys per GitHub Account

The most reliable solution is to use separate SSH keys for each GitHub account and configure Git to select the correct one per repository.

This approach is:

  • Secure
  • One-time setup
  • Scales across many repositories
  • Widely used in professional environments

Step-by-Step Setup

1. Create SSH Keys

ssh-keygen -t ed25519 -C "work-email@company.com" -f ~/.ssh/id_ed25519_work
ssh-keygen -t ed25519 -C "personal-email@gmail.com" -f ~/.ssh/id_ed25519_personal

2. Add Keys to the SSH Agent

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519_work
ssh-add ~/.ssh/id_ed25519_personal

3. Configure SSH Host Aliases

Edit ~/.ssh/config:

# Work GitHub
Host github-work
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_work
  IdentitiesOnly yes

# Personal GitHub
Host github-personal
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_personal
  IdentitiesOnly yes

4. Add Public Keys to GitHub

Add each public key (*.pub) to the corresponding GitHub account:

  • GitHub → Settings → SSH and GPG Keys

5. Update Repository Remotes

This step ensures Git uses the correct account.

# Personal repository
git remote set-url origin git@github-personal:your-username/repo-name.git

# Work repository
git remote set-url origin git@github-work:org-name/repo-name.git

6. Verify Authentication

ssh -T git@github-personal
ssh -T git@github-work

Each command should authenticate as the correct GitHub user.

Optional: Set Commit Author Per Repository

git config user.name "Your Name"
git config user.email "personal-email@gmail.com"

Repeat with work credentials in work repositories.

Conclusion

If you regularly work with multiple GitHub accounts, separating SSH keys per account is the cleanest and safest approach. Once configured, Git automatically selects the correct identity, eliminating permission errors and manual switching.

One setup. Zero friction.