WAG... guestimate it. If you have a paystub with ytd info extrapolate from that. It is trying to help you figure if you still will owe. if you know you are not sending in an additional payment because you have a refund it will not matter.
This year some people owe when they are used to getting a refund since that tax laws and withholding amounts changed. The extension is only to give you time to not to pay your taxes.
Disclaimer: Not a tax professional. Information gathered from internet links. Anything dated in June 2019 was posted in prior years and is before the 2019 limits and changes.
