When you requested your extension you were supposed to pay your estimated tax due. Did you enter the payment you made into your tax return? Go to Federal>Deductions and Credits>Estimates and Other Taxes Paid>Other Income Taxes
E-filing is open for 2018 returns until October 15, 2019. If you still have more tax due when your return is ready to be filed, then you can mail in a check or money order with the return or 1040V voucher, or you can pay directly on the IRS site:
https://www.irs.gov/payments
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
