What is "tax day"?

"Tax day" refers to the April 15 deadline by which Americans must file their federal tax returns each year. In some cases, the deadline is moved back slightly when the 15th falls on a holiday or a weekend, but the 15th is still generally regarded as "tax day."

Some people need more time to organize their documents and prepare taxes, so they file an extension. Even when someone extends his filing, he must still send in payment for any amounts he expects to owe for the year by April 15. The deadline to file with an extension is Oct. 15.