I also think SALT upto 10k limit should be allowable in Line 9b of Form 8960 even if one takes standard deduction for regular tax. https://www.law.cornell.edu/cfr/text/26/1.1411-4 states that “Deductions allocable to both net investment income and excluded income. In the case of a properly allocable deduction described in section 1411(c)(1)(B) and paragraph (f) of this section that is allocable to both net investment income and excluded income, the portion of the deduction that is properly allocable to net investment income may be determined by taxpayers using any reasonable method.”
The "in case of..." does not apply if a person takes standard deduction for regular tax.
Nowhere can I find the clause that if you take standard deduction for regular tax then you cannot claim itemized for NIIT
