In the US, each state has different deadlines and these deadlines sometimes also change. I would therefore say that the best thing to do is search the website for your state (you can find it here http://www.usa.gov/Agencies/State-and-Territories.shtml) and then search for the deadline. In the UK, the deadline is 9 months after the year end for Limited Companies but it’s better to search the companies house website for updated information.