The "high-3" pay includes all items for which retirement deductions are withheld; this includes basic pay, locality pay adjustments and shift differentials, but not overtime (except in special circumstances mainly involving first responders), bonuses/awards, severance pay or buyouts, payments for unused annual leave and credit hours, or "hazard pay" (additional pay for certain "hazardous" duty assignments, such as working in a combat zone). All salaries earned during the "high-3" period are time-weighted, and include COLA's, within-grade (step) increases, and promotions. The "high-3" period normally is the final three years of service but does not have to be (e.g. an employee taking a voluntary downgrade to avoid a reduction-in-force (RIF) could have a high-3 period in an earlier time frame).
