If you have lost or have had your MitID authenticator stolen (MitID app, code display, code reader, or chip), you need to block it.
This means that neither you or anybody else can use - or abuse - that MitID authenticator.
If you get a new MitID app or another MitID authenticator, you can still use MitID.
If your MitID has been or is compromised, you should block your it temporarily. You can do it yourself or you can contact MitID support.
When you block it, all activity on your MitID is shut down. This means that neither you or anybody else can use - or abuse - your MitID.
If you are in doubt and need guidance or help to block your MitID, you can contact MitID support.
Before you block your MitID, you can check if your MitID has been the subject of suspicious activity, which would cause you to block your MitID.
Check your latest activities at the bottom of your profile page.