Thank you to all for helpful messages or shared experiences. I know which of my clients are impacted. Given that I am working 7 days a week on the upcoming deadline & pretty much all year, I have made a practical decision to eat any penalty & wait to see if the payments are withdrawn in June as we have been told (in certain situations). I fear that by re-submitting the 4/15 estimates by mail and/or changing the 6/15 estimates, things may become further muddled & I no longer have confidence in the software. Fortunately, most of what I scheduled for 4/15 were electronic extension payments which I was applying the overpayments to the first quarter estimates. Those went through, but not on 4/15 so that was originally alarming. One of the alerts acted like all electronic payments were going through; they were just delayed. The delay does not seem to be the case with the electronic estimates, only the extension payments. This has not been a good tax season.