Employee Milestones

I'm looking for format Employee Milestones this way. Script below gives me year of service including anniversary date. How do I make it so if employee anniversary (& keep it in this bucket for 30 days after anniversary date) fall in this bucket, names are added automatically? Greg_Deckler 

SELECT *,
       CASE
           WHEN DATEADD(YEAR, DATEDIFF(Year, service_date, GETDATE()), service_date) < GETDATE()
           THEN DATEDIFF(Year, service_date, GETDATE()) + 1
           ELSE DATEDIFF(Year, service_date, GETDATE())
       END AS [ServiceAwardDateNumberOfYears],
       CASE
           WHEN DATEADD(YEAR, DATEDIFF(Year, service_date, GETDATE()), service_date) < GETDATE()
           THEN DATEADD(YEAR, DATEDIFF(Year, service_date, GETDATE()) + 1, service_date)
           ELSE DATEADD(YEAR, DATEDIFF(Year, service_date, GETDATE()), service_date)
       END AS [AnniversaryDate]
FROM [PERSON]