Is federal civil service retirement income subject to Georgia income tax if the retiree only lives in Georgia and has never worked in Georgia?

Where you lived and worked prior to retiring and moving to Georgia has no impact on what is and isn't taxable income in Georgia.  Georgia does not tax Social Security benefits.  Georgia also offers an exclusion for retirement income.  The tax exclusion is up to $35,000 of retirement income earned by people 62 to 64, and up to $65,000 received by those 65 and older.  If you are married, you and your spouse are both eligible, but each of you must qualify separately.  So, if your are 65 or older, and your total retirement income is not greater than $65,000, none of it will be taxed.