When the tax return is due on April 15, 2019. You will either have a tax due or a refund. Even if you get an extension to file or file after April 15 the tax due is still due by April 15.
If you are worried you will owe too much on your tax return you can pay an estimated payment now at <a rel="nofollow" target="_blank" href="
https://www.irs.gov/payments">https://www.irs.gov/payments</a>.
