Filter on Case Statement Output

We have the following case statement "ApproverCheck"

CASE
WHEN [Step] in ('Concur Audit Service100%', 'Concur Audit Service 100%')
THEN
   CASE
   WHEN [Role] = 'Expense Processor(Expense Report Auditing)'
   THEN 'CHECK'
   ELSE 'OK'
   END
ELSE '0'
END

Which w...