Setting Up MFA on a New Phone (and What to Do If You Lose It)

Your MFA app is tied to your phone, which means getting a new one needs a bit of care — do it in the right order and it’s painless; do it the wrong way round and you can end up locked out of your own account.

The golden rule: set up the new phone before wiping the old one

If at all possible, set up your authenticator app on the new phone while you still have access to the old one. Once that’s done, you can safely wipe or hand back the old device. Doing it the other way round — wiping the old phone first — is the most common way people end up locked out.

Setting up your authenticator app on a new phone

1. Install the same authenticator app on your new phone (Microsoft Authenticator, or whichever your accounts use).
2. Sign in to your account’s security settings on a computer, and choose to add a new sign-in method or re-register your authenticator.
3. Scan the QR code shown with your new phone’s app, the same way you did the first time you set it up.
4. Approve the test prompt to confirm it’s working.
5. Once confirmed, you can remove the old device as a sign-in method, if it’s still listed.

Tip

Do this a day or two before you actually need to hand back or wipe your old phone, not the same morning — that way there’s time to sort out any hiccup without being stuck without access.

If you’ve already lost or wiped the old phone first

This is recoverable, it just needs support to step in and verify your identity manually, since the normal self-service route (using the old device to approve setting up the new one) isn’t available to you anymore. Contact support and explain the situation — the sooner you flag it, the sooner you’re back in.

If your phone is lost or stolen (not just replaced)

Treat this the same as a lost or stolen device — contact support immediately. Beyond the MFA app itself, a phone that was receiving your codes or prompts is a route into your account for whoever has it, so speed matters here too.

A good habit: register a backup method

If your account allows more than one MFA method, register a second one — a backup authenticator on a tablet, or a YubiKey kept somewhere safe — so a single lost phone doesn’t leave you with zero ways to sign in while it’s sorted out.