Below is the text of an email I received yesterday - and which, I think, would be prudent to assume also applies to those of us holding existing Govt Gateway accounts for State Pension checking and HMRC tax return purposes, pending eventual migration to GOV.UK One Login:

You need to update your GOV.UK One Login or you may soon lose access to services on GOV.UK.

To keep your GOV.UK One Login safe, we’re changing how we send the security codes you use to sign in.

You can no longer get a security code by text message if your phone number is registered outside the UK.

You need to update your GOV.UK One Login to use an authenticator app or UK mobile phone number.

Go to GOV.UK and search for ‘One Login’ to sign in and change how you get security codes.

Authenticator apps

An authenticator app creates a security code that you enter in the same way as a code you get by text message.

You can use an authenticator app on your smartphone, tablet or desktop computer. Most authenticator apps are supported, including Google Authenticator and Microsoft Authenticator.

You may find apps called GOV.UK ID Check or GOV.UK One Login. These are not authenticator apps and you cannot use them to get security codes. They are used to prove your identity.

If you cannot use an authenticator app and you do not have a UK mobile phone number, then you cannot use GOV.UK One Login to access government services. Services will offer another way to prove your identity and sign in.

13 hours ago, OJAS said:

Below is the text of an email I received yesterday - and which, I think, would be prudent to assume also applies to those of us holding existing Govt Gateway accounts for State Pension checking and HMRC tax return purposes, pending eventual migration to GOV.UK One Login:

You need to update your GOV.UK One Login or you may soon lose access to services on GOV.UK.

To keep your GOV.UK One Login safe, we’re changing how we send the security codes you use to sign in.

You can no longer get a security code by text message if your phone number is registered outside the UK.

You need to update your GOV.UK One Login to use an authenticator app or UK mobile phone number.

Go to GOV.UK and search for ‘One Login’ to sign in and change how you get security codes.

Authenticator apps

An authenticator app creates a security code that you enter in the same way as a code you get by text message.

You can use an authenticator app on your smartphone, tablet or desktop computer. Most authenticator apps are supported, including Google Authenticator and Microsoft Authenticator.

You may find apps called GOV.UK ID Check or GOV.UK One Login. These are not authenticator apps and you cannot use them to get security codes. They are used to prove your identity.

If you cannot use an authenticator app and you do not have a UK mobile phone number, then you cannot use GOV.UK One Login to access government services. Services will offer another way to prove your identity and sign in.

I didn't get the email. Probably because I am already set up to use the Google authentication app to validate my Gov.uk login.

2 hours ago, Mutt Daeng said:

I didn't get the email. Probably because I am already set up to use the Google authentication app to validate my Gov.uk login.

Quite possibly. Following receipt of the email I changed the security access on my Govt Gateway account from my Thai number to the UK giffgaff one I use to access my UK bank account, and noticed for the first time that the authentication app option was also being offered. So it goes without saying, I think, that it would be much more convenient for those who presently use Thai numbers to access their Govt Gateway accounts to download a suitable authentication app rather than wait for a giffgaff SIM card to turn up in the post from the UK (assuming that giffgaff still send these to Thailand).

Incidentally, one thing I should have mentioned in my previous message is that the official advice from HMRC is for us to sit tight and continue using our Govt Gateway accounts until such time as we are told to create a GOV.UK One Login replacement:

https://www.gov.uk/guidance/accessing-hmrc-online-services-using-govuk-one-login