If you do not pay all your required estimated tax for 2009 by January 15, 2010, or file your 2009 return and pay the tax by March 1, 2010, you should use Form 2210-F, Underpayment of Estimated Tax by Farmers and Fishermen, to determine if you owe a penalty. If you owe a penalty but do not file Form 2210-F with your return and pay the penalty, you will get a notice from the IRS. You should pay the penalty as instructed by the notice.
If you file your return by April 15, 2010, and pay the bill within 21 calendar days (10 business days if the bill is $100,000 or more) after the notice date, the IRS will not charge you interest on the penalty.
Do not ignore a penalty notice, even if you think it is in error. You may get a penalty notice even though you filed your return on time, attached Form 2210-F, and met the gross-income-from-farming requirement. If you receive a penalty notice for underpaying estimated tax and you think it is in error, write to the address on the notice and explain why you think the notice is in error. Include a computation similar to the one in Example 1 (earlier), showing that you met the gross income from farming requirement.