Who Calculates Release Dates, the Court or the Jail?

Release dates are calculated by the Department of Corrections, not by the court or the jail. The jail holds him and the court handles sentencing, but the actual release date math happens at the DOC level once all the paperwork is processed. That is why the jail may not have a firm date to give you, particularly when his situation involves multiple overlapping matters.

Right now his case has moving parts that make a release date harder to nail down. He is serving time on a new charge through November, and then he faces a separate revocation hearing for the state case. Until that revocation hearing resolves, no one can calculate a final release date with confidence. If the revocation goes against him, additional time gets added and the whole calculation changes. If it resolves favorably, the picture clears up.

The new charge being handled at the county level should not affect his existing state sentence unless he is convicted on it, which would bring a new sentence into the mix. Right now he is serving on what is already on the books.

Once the revocation hearing in November produces an outcome, the DOC will have everything it needs to compute and post an accurate release date. That is the point at which you will get a reliable answer. Calling the DOC directly after the November hearing is the right move.