The $10,000 limitation on state local and foreign income taxes paid is correct.
In the instructions for posting box 9b of 8960 it refers to Deductions subject to AGI limitations under section 67 or section 68 which reads:
"Any deduction allowed against net investment income that, for purposes of computing your regular income tax, is subject to either the 2% floor on miscellaneous itemized deductions (section 67) or the overall limitation on itemized deductions (section 68) is allowed in determining net investment income, but only to the extent the items are deductible after application of both limitations."
Please see: Topic No. 503 Deductible Taxes Under Overall Limit.
"As an individual, your deduction of state and local income, sales, and property taxes is limited to a combined total deduction of $10,000 ($5,000 if married filing separately). You may be subject to a limit on some of your other itemized deductions also.
Please refer to the Instructions for Schedule A (Form 1040) and Topic No. 501 for the limitations. Page Last Reviewed or Updated: 03-Mar-2023
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