We can use a query like below to get Quarter’s Start and End Date for a given date.

DECLARE @AnyDate DATETIME
SET @AnyDate = GETDATE()

SELECT @AnyDate AS 'Input Date',
  DATEADD(q, DATEDIFF(q, 0, @AnyDate), 0) 
                        AS 'Quarter Start Date',       
  DATEADD(d, -1, DATEADD(q, DATEDIFF(q, 0, @AnyDate) + 1, 0)) 
                        AS 'Quarter End Date'

Note the Quarter End Date returned by the above query is without time part. If we need to generate a report for a quarter then we need to include all the transactions happening on the last date of the quarter till mid night. Then in the query instead of comparing with last date of the quarter we can check whether it is less than the next quarter start date.

Below query shows how to get Quarter’s Start Date and the Next Quarter Start Date for a given date.

DECLARE @AnyDate DATETIME
SET @AnyDate = GETDATE()

SELECT @AnyDate AS 'Input Date',
	DATEADD(q, DATEDIFF(q, 0, @AnyDate), 0) 
                               AS 'Quarter Start Date',       
	DATEADD(q, DATEDIFF(q, 0, @AnyDate) + 1, 0) 
                               AS 'Next Quarter Start Date'