- Final deadline to file 2017 individual tax returns (with extension) - (Forms 1040, 1040EZ).
- Last day the IRS will accept an electronically filed tax return for the year 2017. If filing after October 15, you'll need to mail in your tax return for processing.
- Final deadline for calendar-year Benefit Plans (with an extension) to file Form 5500.
- Final deadline to fund a SEP-IRA or solo 401(k) for tax year 2017 if you requested an automatic extension of time to file.