HSA contribution deduction

[mattb1155]

Why am I not getting a full deduction for my personal contribution to my HSA.  If I enter $0 in HSA my tax due is $1,800.  When I enter $4,150 in HSA my tax due is $900.

[MinhT1]

Your personal contribution to your HSA is a deduction which reduces your taxable income. It does not reduce your taxes due dollar for dollar.

Your contribution to your HSA has reduced your taxable income by $4,150 and your tax liability by $900, which is correct. Your marginal tax rate is 22%.