User blog comment:DevonAndersen/iCarly Ending After Season 5 is Done/@comment-3048370-20110816011523/@comment-3123404-20110818163129

Except it won't be Season 6. After Dan had shot "13 episodes" for Season 4 from May 2010 to September 2010, in October of that year Nick ordered there to be 13 more episodes for the season to bring the count up to 26. Then in April, they renewed the show for a fifth season happening next year in 2012. So the episodes Dan had shot from May 2011 to July 2011 are episodes added to Season 4 to complete it's 26 episode count that will carry out through the 2011-2012 season. Season 5 will take place in the 2012-2013 season.