This has been answered in below FOI request that HO case worker do not have direct access to electronic access to information held by another government department. They make request to HMRC seeking for that information. It would be helpful, if someone else can confirm this. https://www.whatdotheykn...

I am also looking for someone who can confirm, if it's true that Home Office/PEO's are only referring to HMRC database till Jan 2015