How to find XXth day of previous month in SQL server?
DECLARE @d DATETIME = '20140311', @dm TINYINT = 26;

SELECT DATEADD(DAY, @dm-1, DATEADD(MONTH, -1, DATEADD(DAY, 1-DAY(@d), @d)));


Result:

2014-02-26 00:00:00.000