Assuming Ohio is your HOR and you are stationed outside OH: When you file a joint OH return, you indicate that she is a non resident and you are a full year resident.
Ohio does a convoluted
tax calculation for non-residents/part year residents. It calculates tax on
total income, then it calculates a non resident/part year resident credit,
which it subtracts from the tax it calculated on the total income. The credit
is calculated as your non-Ohio income divided by Total adjusted Income
multiplied by the total tax. TurboTax (TT)
does this by allocating your
income as either Ohio
or non-Ohio. W-2 income will be allocated by the state name abbreviation shown
in box 15
of your W-2. TT will ask you, item by item, in the state section, how much of
your other income is Ohio
or non-Ohio income. Make sure that her non-Ohio wages show
XX (Other state postal abbreviation) in box 15 of her W-2 screen, with the XX state amount
in box 16.