for dallas texas
Criminal Defense Attorney
State jail time must be served day for day; there is no credit for good behavior. A state jail inmate may be credited by the judge his county back time. Whether or not he was actually credited for that time depends on what the judge gave him at sentencing.
I would recommend giving his attorney a call or visiting the district clerk in Dallas County to see how much time was credited by the judge. That information should be on or in his file.