Hello All,
I asked the BS migrationsamt and they just linked me to eUmzug so I'll try here.
I will move to BL with a lease starting 16th July but my current lease doesn't terminate until 31st July. I just want to know which date should be considered my moving date since I have 2 rental contracts active at the same time.
If either date can be used from the perspective of migrationsamt is there any reason to choose one or the other from my side?
I can't see it making a lot of difference from your side, TBH. Taxation is normally lower in BL, but unless you're still on withholding tax the full year will be calculated in the new canton regardless of moving date.
I suspect that the new canton, if pushed, would say that the day you move to the new place will be the date from which you should be registered there. Deregistering from BS before the lease end date should not present any complications.
We checked it out and for us BL was in general more expensive than BS - on pretty standard expat salaries.
I think it used to be lower tax but not really any more.
https://taxjungle.ch/ch-en
Rental contract terms are utterly irrelevant. It's when you move. Assuming you move into your new place 16th July, that's the date you register/deregister on.