The UK Government has decided not to extend the Custom Support Agreement (CSA) with Microsoft, meaning government departments will now have to find new software solutions and migrate.
The Office of the Chief Technology Officer said that the decision to pull the plug on support for the OS was taken last month by general agreement.
The CSA signed in 2014 expired in April this year.
The Office of the Chief Technology Officer said: "There has been good progress in moving away from Windows XP across departments and government organisations and with many public bodies this transition is complete.
"We expect most remaining government devices using Windows XP will be able to mitigate any risks, using the CESG guidance. Where this is not possible, they may need to review their own short term transition support."
