Bud,
I only make changes about every other year to only my CSR tax withholding after I know how much the annual COLA have increased my over all annual gross combined income the previous and current tax year, because my USAFR pay have no taxes being withheld unless I change it through DFAS and my meager SSA pension is not taxed and my VA Comp is nontaxable, but I'm not complaining as long as to what I owe to Federal isn't too much before the IRS deadline for filing our joint annual income taxes, which thankfully is now pretty simple to do with the simple 1040A form and lucky I don't have to bother with additional ITINs since it's just my wife and I with nothing to declare and or itemize, because we left nothing behind in California!
Now I just have to figure out how to change our "State of Residency" to a State that has no State tax, even though we do not pay any state tax in California while residing in the Philippines the entire tax year!