Should box 12dd include pre and post tax deductions?

[rjs]

There is no box 12dd. I assume you mean code DD in box 12. (Boxes 12a, 12b, etc. are just part of box 12.) Code DD is just for your information. It does not affect your tax return. It's supposed to be the total cost of the health insurance provided by your employer. Total cost would include everything paid for your health insurance, whether it's pre-tax or post-tax, and whether it's paid by you (deducted from your pay) or paid by the employer.