When are taxes due? can the internet tell me? no search on “taxes due” “tax due date” “tax filing date” or whatever came up with anything. You’d think the IRS page would have something big on their front page, but no. Like most gov pages, they really are not user friendly at all. Finally, Wikipedia helped me out. Here’s the skinny. Taxes in America (the united states of, that is) are due on april 15 unless that day falls on the weekend (such as this year, 2006) in which case they are due the following Monday. Post offices stay open late that day, till midnight, for all of the procrastinators.