When signing in you may receive the message that "The government service needs to be more confident it's you". The reason for this is that the service you are trying to access requires a higher level of identity verification than you currently hold.
When you continue you will be asked to add additional information regarding your identity (shown in the screenshot above). This is a one time process as this will increase your identity verification level permanently.
If however you fail the uplift you will keep your current level of identity verification but it will limit what government services you can access until such time you are successfully able to.