Congrats to all you guys you passed!
It was easier to look up the answer than to look up the question. Here it is:
An individual's estimated tax payments must be 100% (110% if prior year AGI > $150k) of the prior year's tax or 90% of current year's tax.
A corporation's is 100% of PY or 100% of CY, but paying 100% of PY is not an option for a large corp (taxable income of $1M + during any of the past 3 years).
Estimated tax payments are due the 15th of the 4th, 6th, 9th, and 12th months of the year for corporations. For individuals, it's the 15th of the 4th, 6th, 9th, and 1st month.
Sounds right? It IS easier remembering this stuff when we've talked about it in this group.