Tax deadline: 9 things to know including penalties for filing late as last day is today May 17 2021, 6:28 ET Updated: May 17 2021, 6:36 ET TIME is running out for Americans to file their tax returns, with the extended deadline today, May 17. We round up nine things you need to know, including the penalties for filing late. 1 1. The deadline is today - but some states offer more time In March, the Internal Revenue Service (IRS) extended the tax return deadline for federal taxes from April 15 to today, May 17. The IRS also decided to push back the deadline last year due to the pandemic. The M...