[drdec]

The reason for the reasonableness requirement is that in a normal year, you are required to pay that estimate on Apr 15 when you file the extension. If the estimate was too low, the IRS wants their pound of flesh.

In a year where no one has to pay until Jul 15, there is no point in enforcing that clause.

There is benefit to people in pushing the filing deadline even after the payment deadline has been changed as it does reduce the paperwork burden, especially for those who rely on paid preparers.