TurboTax treat HSA as income

 am using TurboTax Deluxe to prepare 2018 tax return filing.  I contributed $3600 and my employer contributed $1500 in 2018.  My W-2 shows 12W as $5100, which is correct based on IRS.  However, when I entered 12W and $5100 in TurboTax, Turbotax treated it as "Other Incomes or Loss: $5100".  This resulted in an increase of $1170 in my Federal and state tax.  Since HSA is pretax, why doesTurboTax treat HSA contribution an an income?  Can anybody help me?  Thanks.