@chesterspal generally your taxes for a year must be paid in quarterly. 1/4 for each tax quarter. the due dates for the estimated tax payments are around 4/15, 6/15/ 9/15 and 1/15 of the following year. and withholding ifor the year is deemed paid equally each tax period but when filing you can elect to use the actual amount.
generally, the taxes that must be paid in on a timely basis to avoid penalties are either 90% of the current year taxes or 100% of the prior year taxes (110% if the prior year adjusted gross income was over $150K))
since most taxpayers don't know what their taxes will be for the current year they fall back on the prior year exception. state laws vary
