The difference is almost certainly just the code "W". The amount for code "DD" has already been removed from wages in boxes 1, 3, and 5. Please enter all codes amounts just as you see them on the W-2.

Code "W" in box 12 of the W-2 indicates the sum of contributions to your HSA by both your employer and you through a payroll deduction scheme.

Yes, this amount is normally not taxable - but only if you have completed the form 8889. You enter the data for this form by going to Federal Taxes->Deductions & Credits->HSA, MSA Contributions and starting the HSA interview.

Please proceed all the way to the end of the interview, as the IRS considers the contributions and distributions (if any) as taxable until the 8889 is completed. At the end of your interview, you should normally see your taxable income drop as TurboTax correctly moves the Code W amount back into the not-taxable category.

For a complete list of the codes, please see https://ttlc.intuit.com/replies/3300234.