If you received one Form W-2 from DFAS, part of which was for active duty and part for reserve duty, check that the W-2 was for active duty. 

I am in a similar situation: my single W-2 contains mostly reserve duty pay and some active duty pay. I am an Arizona resident, so only the reserve pay is taxable (AZDoR Pub 704, Q26). When I check that the W-2 is active pay (as advised above) in TurboTax, the Arizona form states I owe no taxes at all. This seems incorrect to me. Please advice.

Is the active-duty pay for training purposes (basic or advanced) or was it for Annual Training or statute active duty?

It was a yearly Annual Training which lasted for 45 days and was considered active duty.

@TurboTaxToddL Any luck in getting an answer? Thanks in advance for your assistance.

That was a pretty long AT!
For retirement purposes, it does count as "active-duty" time, but AT is still considered reserve pay for tax purposes. You'd have to be mobilized or at least on extended active duty orders.

@TurboTaxToddL Thank you for the information. If it helps for further clarification, I'm in a unique program where my medical education is paid for by the US Navy. This most likely accounts for the long AT period.

To confirm, I do not select "active duty military" for the "Do any of these uncommon situations apply to the W-2?" section. Is this correct?

That would be correct. BTW, two of my children are Navy doctors, both at Walter Reed.

(well, one is in Iraq at present)

@TurboTaxToddL Thank you for the information and I look forward to working with them soon!