I missed Dead line for filing 2018 tax return, Need to file an extension so that I do not have to pay a penelity

[hilton1]

What do I have to do to file an Extension?

[SteamTrain]

Extension must be filed by the deadline too. So it's too late

Just get it done and e-filed as soon as you can.   IF you have a refund, there's no penalty.  If you owe a balance due, the penalty/interest wouldn't be too bad if you don't owe too much extra anyhow....and you get it in the next couple weeks