My understanding is that the line9b is allowed only when tax payer claims itemized deduction.
From instruction 8960 Reasonable method allocations, "State, local, and foreign income taxes IF PROPERLY DEDUCTED on your return when calculating your U.S. regular income tax."
Then, SALT ($10000) limits the line9b as well?
If my state tax is $15000 and claim itemized deduction, only $10000 can be allocated to NII?
It seems that turbotax doesn't limit the allocation by SALT
