Yes, when asked to provide your "federal service to date" for tax purposes, it typically refers to the date you began your federal employment, which includes your entry date into military service. According to the U.S. Office of Personnel Management (OPM), Chapter 5, page 6. the Service Computation Date (SCD) is "a date, either actual or constructed,that is used to determine benefitsand is generally based on how long the person has been in the Federal Service."