Net tax free interest different on FED and CA state return

The same issue on both mine and my daughter's return.  When I look at Fed tax free interest on 1040 it does not match what is on the CA state Interest/dividend worksheet.  They aren't off by a lot but don'r understand why not exact.  We have to split income between two states so we need to understand Bond interest minus bond premium by date to know which state gets what but difficult when our actual records don't match what turbotax is doing. Our records match the federal amounts but not the info transferred to CA.