Why do i lose a deduction if state and local taxes are less than 10000

[rbh]

my state and local taxes were less than $10,000 but I lost 17891 in deductions

[AnthonyC]

Can you clarify where you are seeing this loss of deductions?  Is it the Federal Deductions and Summary screen?

A few notes on items you are probably seeing on that screen:

Property taxes and also included in that $10,000 limit for state and local income taxes.  So, if you had $8,000 in property taxes and $8,000 in state and local income taxes, then you would lose $6,000 in deductions due to the limit.

Many miscellaneous itemized deductions, such as job-related expenses for W2 employees, are also no longer deductible.

There are no longer any personal exemptions.  In the past, you received an exemption amount of $4,050 for each person on your return (so a family of four would be $16,200).  These exemptions, while not technically deductions, would show as deductions in the summary amounts.