In IRS Notice 2020-23 released late last night, the IRS has adjusted the due date of the 2020 second quarter estimated tax payments from June 15 to July 15, 2020. This means that the first and second quarter estimates are now both due on 7/15/2020. Previous to this notice the second quarter estimate was due before the first quarter estimate, causing confusion.
In the same notice the IRS also extended the time to file some amended returns that normally would have lapsed on 4/15/2020. The time to seek refunds from these 2016 tax filings has now been extended to 7/15/2020.