is it really automatic and easy to get an extension on paying taxes form 4868?

Answer 1

The extension is easy to get, but it is an extension on **filing** your return, not on **paying** your income tax. You still need to pay what you owe, if anything, by April 17 or face a penalty and interest.

Answer 2

The extension is to file, not to pay. You still have to have enough paid in by 4/17 to cover your tax liability for the year or you'll be subject to interest, and possible penalties, on the underpayment.