Can we pay our 2018 Federal tax? now and pay online? Filed extension. Please advise.

[VolvoGirl]

You can pay at <a rel="nofollow" target="_blank" href="https://www.irs.gov/payments">https://www.irs.gov/payments</a>
You should pay as soon as possible.  The tax due was due on April 15 so Interest might be accruing.  

[Anonymous]

too late to get an extension and that's only good for giving you more time to file your taxes not pay what's due.

be prepared for late filing penalties and interest.   

The late filing penalty is 5% of the additional taxes owed amount for every month (or fraction thereof) your return is late, up to a maximum of 25%. If you file more than 60 days after the due date, the minimum penalty is $205 or 100% of your unpaid tax, whichever is less.