HMRC have provided us with the following update regarding the Government Gateway.
"As part of the work needed to update and enhance the Government Gateway, we are changing the location of a number of Agent User Interfaces on 10 September 2018. This may result in users who attempt to access pages being presented with a blank screen, page that can be read but not updated or a message advising them to proceed to a different link.
In any of these scenarios, users should access the following link where they will be able to log in and proceed as normal.
We apologise for any inconvenience this causes users and we would be grateful if you could make your members aware."