Date Differences & CASE

I have written the SQL below and need to change the case. I need to say that if today’s date (get date) is between <> 4 weeks of sv_latest_appraisal then = Outstanding. Can this be done in SQL? I know it is very specific so not sure. Please help! Sam

SELECT Employee.FORENAME AS Forename,
Employee.SURNAME AS Surname,
Employee.LOCATION AS Location,
Employee.DEPARTMENT AS Department,
Employee.STARTDATE AS Startdate,
Sv_latest_appraisal.NEXT_APP AS Next_app,
Sv_latest_appraisal.USR_EAR_TYPE AS Usr_ear_type,
Sv_latest_appraisal.USR_EAR_TYPE_NEW AS Usr_ear_type_new,
CASE
WHEN Sv_latest_appraisal.NEXT_APP <= getdate() THEN 'OVERDUE'
WHEN Sv_latest_appraisal.NEXT_APP >= getdate() THEN 'NOT DUE'
WHEN Sv_latest_appraisal.NEXT_APP = getdate() THEN 'DUE TODAY'
ELSE 'UNKNOWN'
END
FROM (dbo.EMPLOYEE AS Employee
INNER JOIN dbo.SV_latest_appraisal
ON Employee.EMPLOY_REF = Sv_latest_appraisal.EMPLOY_REF)
INNER JOIN dbo.JOB AS Job
ON Employee.JOB_REF = Job.JOB_REF
WHERE (Employee.LEAVER = 0)AND (Employee.LOCATION LIKE 'GE')