"...should be tagged and supervised for the rest of their sentence."
All prisoners are released from prison on licence under probation supervision from when they leave prison until the end of their sentence.
In cases where a prisoner has less than 12 months on licence after their release then the probation supervision is extended to 12 months.
Eg In the past, if a prisoner was sentenced to say 20 months then they would spend 10 months in prison and 10 months on licence, that is 50%. However, since their period on licence was less than 12 months then their period of supervision would be extended.
This was then reduced in 2024 under the Labour government so that if a prisoner was sentenced to 20 months then they would serve 8 months in prison and 12 months on licence, or 40%.
The latest changes mean that, from 1st October, if a prisoner has been sentenced to 20 months then they will spend 6 2/3 months in prison and 13 1/3 months on licence, that is 33%.
This applies to all prisoners except those convicted of violent or sexual crimes who would still have to serve 50% in prison. There are also some prisoners that are required to serve longer than this.
[EDIT]
Although, just thinking about it, I was walking down the street a couple of days ago and noticed a man in his 50s walking towards me (since it was so hot he was wearing shorts).
I could see that he had an ankle tag. That did really surprise me (I turned to have another look after I had walked past him just to make that I wasn't mistaken).
On second thoughts though, if the scheme mentioned hasn't started yet then he definitely wasn't a sex offender as they are specifically excluded from the current Home Detention Curfew that lets offenders out of prison even earlier than early release.