In my W-2 form under box 12, their are two codes DD (cost of employer sponsored health coverage. The amount reported with Code DD is not taxable.) and D, shall I report only D and not DD? Box 14 shall I report both Y(Pretax flexible spending accounts) and V (pretax FEHB Incentive)?

You report none of these.

D: This is your salary deferral (since you mentioned the FEHB I assume this is a TSP contribution). Box 1 wages already reflect this.

DD: This is an information-only item required by the Obamacare legislation. Its purpose is to let people know how much their health insurance is costing in total. It doesn't affect your return.

Y: This reduces the amount of deductible expenses. For example, if you set aside $2,000 for health care expenses the first $2,000 of those expenses would not be available on Schedule A.

V: I'm not familiar with this, Do you perhaps have an HSA? It's something related to health care/insurance, and in general such pre-tax payments reduce the amount of expenses otherwise deductible on your return.

Phil
Rule Your Retirement Home Fool