Start of the period	End of the period	Due date
March	2011-01-01	2011-03-31	2011-04-15
June	2011-04-01	2011-06-30	2011-07-15
September	2011-07-01	2011-09-30	2011-10-17
December	2011-10-01	2011-12-31	2012-01-16