Two-factor authentication backup planning addresses the obstacle that stops most digital estate plans at the final step. Passwords are recorded, the vault is accessible, authority is documented — and the accounts still will not open, because each one demands a code from a device or app nobody can reach.
The mechanism causing this is the point of two-factor authentication: possession of something physical. A code generated by an app on a locked phone, or texted to a number that gets cancelled when the carrier is notified of a death, is unavailable precisely when your executor needs it. The security feature works exactly as intended, against the wrong person.
The specific trap is authenticator apps. Unlike a password, the codes are generated from a secret stored on the device itself, so a lost or wiped phone destroys the ability to generate them. Most services issue backup or recovery codes when two-factor is enabled, and most people close that screen without saving them. Those codes are usually the intended escape route.
Planning for this means saving backup codes for important accounts into the same secure storage as credentials, keeping the phone's own passcode recoverable, and recognizing that the carrier account is itself a critical asset — cancelling a phone line early can lock a family out of everything that authenticates by text.