Do you add all numbers in Box 12 for HSA contribution?

[BillM223]

No, only the number with code W in box 12 is the HSA contribution, called the "employer's contribution" - actually, this is the sum of what the employer contributed PLUS whatever you contributed by means of payroll deduction.

But why do you ask? Once you enter your W-2, you don't enter the code W amount anywhere else in the tax return.