From this, I assume it is okay to pay estimated tax anytime in the year, after an unexpected income event, right?
I’ve got the converse question. My wife is a freelance writer, with an inconsistent income, so we do estimated taxes based on a generous estimate. We often do not pay fourth quarter estimated payments if we have overestimated her income. (We run the numbers before we do this.) We always wind up with an overpayment anyway. Is this acceptable - in other words, does the IRS only care about the sum of the estimated payments, not their spacing?
The “estimated tax penalty” is really just the interest you owe on not paying on time. You had the cash, the IRS didn’t you owed the IRS, thus you pay interest. They call it a “penalty” so that it isn’t deductable.
Generally, you can also get a ETP waived if your underpayment was a one time only thing. In other words, if you had a one time windfall, the Service center might impose a Penalty. But you can appeal that penalty, and usually win if you got a refund the year before. Khadaji- you have i think 2 years to dispute that. Ignorance IS an excuse with Tax laws.
As to Voyagers question- "it depends’. It depends on whether it was a “one time windfall” and when in the year it was. If you got a big check in the spring, and last year you owed, you’d be expected to pay the Government as the income came in. That is to say- now, not in December.