For TY2021 the 4th 1040ES payment was due on Jan 18, 2022.
For context, this dispute is for not filing an Extension and making payment. But the extension was filed and an estimated payment (over payment) was made by April 18, 2022. She has proof from the online service and the bank, so she's going to contest it.
But I thought it was strange how the IRS decided to assess interests that did not happen yet. They thought it'd take a whole week for the mail to get to her. The IRS must not trust USPS.
