Can I still file for extension on my 2018 taxes? will it cost me?

[IreneS]

No, you cannot file for an extension after the tax return due date, April 15, 2019.  You should complete and file your return as soon as you can. 

If you think you're going to have a balance due, you should make a payment now on the IRS website to reduce any interest/penalties.  You can make the payment by clicking this link: https://www.irs.gov/payments