Prior year's tax method:
If your quarterly withholding + estimated tax in 2023 are at least 100% / 4 = 25% ( 110% / 4 for certain high income taxpayers) of your 2022 tax, there will be no penalty on your 2023 tax return, regardless of any jump in income.
you are protected from a sudden capital gain at year end, for example.
you know your prior year's tax when you file by April 15, which is also the first estimated tax payment due date.
there is no "square up at year end" method.
