Extension vs. Payment
Taxpayers can get an automatic 6-month extension by submitting Form 4868, Application for Automatic Extension of Time To File U.S. Individual Income Tax Return. This form extends the time to file until October 15.
This is only an extension to file, not an extension to pay. If taxpayers do not pay the tax due by April 17, they will owe interest and may be charged penalties. Refer to Form 4868 Instructions, How To Make a Payment With Your Application.
Later, when taxpayers file their return, they report the payment made with Form 4868 on the applicable line in the Payments section of Form 1040.
If the April 15th deadline falls on a Saturday, Sunday, or legal holiday, the deadline is the next business day.
One of Bernice's Forms W-2 was lost in the mail. She requested a copy from her former employer, but it did not arrive by April 17. She filed for an extension, calculated the amount of taxes owed based on her final pay stub from that employer, and paid the $243 that was due. When she finally received her Form W-2, she filed her return and reported the $243 on the applicable line in the Payments section of Form 1040.