2018 tax extension has been filed. How to handle 2019 Payment 1 estimated taxes?

[Starting-2018]

I am required to pay 2019 estimated taxes. I have a refund coming for 2018, which has not been issued yet because of extension. What am I supposed to do for the April 15th payment for 2019 estimated taxes?  Can this be considered as I applied my refund to that payment?  Or I need to pay IRS now because taxes have not been filed yet so refund is still considered "hypothetical"?

[JulieR]

You'll want to make the first 2019 estimated tax payment now, then when you file your return, if you are receiving a refund, you may choose to apply it to your 2019 estimated payments if you wish to. 

You can make a 2019 estimated tax payment online with IRS Direct Pay.  The following FAQ provides additional options for making your estimated tax payments. https://ttlc.intuit.com/replies/3301258