The last of the four estimated tax payments for calendar year 2011 is due Jan. 16 (the fourth estimated tax payment is ordinarily due Jan. 15, but that day is a Sunday this year). Have you paid in enough during the year? If not, what will happen and what can you do about it?
How much do you have to pay?
Ideally, the four estimated tax payments you make each year will add up to your tax liability for the year. However, if your income varies substantially from year to year (as it does for many real estate professionals), it can be hard to estimate how much you must pay during the year. If you don't pay enough estimated tax, the Internal Revenue Service will impose a penalty.