To add a primary/backup method:

• Navigate to Settings > Configure Chargebee > Checkout and Self-serve portal > Advanced settings
• Enable ‘Allow customers to add multiple payment methods' setting.

Note: Allow customers to add multiple payment methods is available only in selected plans. To know more, visit Chargebee's Plans and Pricing page

Once this is done your customer can choose to mark a payment as Primary or Backup by logging in to their self-serve portal.

In case your customer has already added multiple payment methods to their subscription, they can set primary/backup payment methods by selecting the corresponding card and clicking the ‘Set this as primary or backup' link.

Note: You can also set a payment method as primary or backup using the Chargebee app. Click here to know how.