I received a payment from my military retirement ROTH savings plan. will i need to add that considering the taxes should have already been withdrawn?

[dmertz]

Yes, you are required to enter the Form 1099-R reporting this distribution.  The tax liability resulting from this distribution is not determined until you prepare your tax return.  Whatever was withheld for taxes is simply credited toward your overall tax liability on Form 1040 line 17 and does not apply to any particular item of income.