Bob - yes moving from AZ - and I don't have issues with that part since that's where I practice.  It's the tiny piece of CA residence that I'm concerned about.  Normally I don't do CA returns but I'd like to assist this client for one last year if possible.  And yes - the moving truck and client leave AZ on 12/8 - a clear separation date between states.  House sold in AZ and new residence rented in CA.  Although your logic is reasonable, that's not an issue for this client.  But of course I'm not preparing the return for at least another couple of months.  But the calculation you refer to here is very helpful - I couldn't find anything like that in my research.  That's something that will be easily estimated since they will only be in CA resident in 2025 for 3 weeks.  1 SS payment - apparently not taxable in CA but probably partially taxable on the Fed level, plus whatever small activity the broker statement spits out during those 3 weeks.  AZ house proceeds will not be taxable on Fed because the profit will be way less than $250k.

I'm hoping to get enough information and backup to determine that client will not have to file a CA return for 2025 at all.  Do you think I have to file simply to get to that percentage calculation?  Client will definitely file for Fed and AZ.