Why are estimated taxes due April, June, September, January instead of April, July, October, January? Quarterly is every 4 months is it not?

[BMcCalpin · Accepted solution]

Actually, "quarterly" is every three months. 12 months divided by 4 = 3 months.

Yes, it seems odd that the quarterly due dates are April 15th, June 15th, September 15th and January 15th, but there is method to the madness.

April 15th is because the due date of the 1040 is April 15th, and it didn't make sense have them due on different dates. June and September are OK, but the last quarter is due on January 15th, because it needed to be after the end of the tax year, so that the taxpayer could calculate their real income for the year to know exactly what the last payment should be.

Why January 15th and not January 1st? I guess that the IRS is enamored of the 15th, and besides, the day after New Year's Eve would not be a good day for any tax payment...