FYI:
if you're in a combat zone, you can file an extension and won't have to pay penalties, even if you owe.
from the irs website:
The IRS automatically extends the deadline for filing tax returns, paying taxes, filing claims for refund and taking other actions related to federal income tax for U.S. Armed Forces personnel serving in a combat zone. The IRS also extends the deadline for those in the U.S. Armed Forces deployed overseas away from their permanent duty station in support of operations in a qualified hazardous duty area but who are outside that area.
The deadline for filing returns, making payments or taking any other action with the IRS is extended for at least 180 days after:
The last day of qualifying combat zone service, or
The last day of any continuous qualified hospitalization for injury from the combat zone.
The IRS is currently working with the military to obtain information about reservists and regular military personnel serving in combat areas. During this interim period, people in the military, their spouses or their authorized representatives have several options to claim the filing extensions or filing exclusions:
When filing returns, mark “Combat Zone” at the top of the form along with the date of deployment.
Contact the IRS through the special e-mail address at IRS.gov. Correspondence should include the name, stateside address, date of birth, and date of deployment of the service member. (No Social Security numbers should be included in the e-mail.) The IRS emphasizes only military-related e-mails should go to this address. Calls can also be made to the main IRS help line at 800-829-1040.
These two steps also apply if a notice inadvertently goes to an individual serving in a combat zone or his or her spouse. The notice can be deferred by following the e-mail steps or by sending the notice back to the IRS marked with the words “Combat Zone” and the date of deployment.
The IRS plans to take additional steps and provide additional guidance on issues involving military personnel and combat zones. This new information will also be posted to the Armed Forces page on IRS.gov.
http://www.irs.gov/newsroom/article/0,,id=108523,00.html
Q-12: My son is a member of the U.S. Armed Forces who has been serving in a combat zone since March 1. Is he entitled to an extension of time for filing and paying his federal income taxes? Are any assessment or collection deadlines extended?
A-12: For both questions, the answer is yes. In general, the deadlines for performing certain actions applicable to his taxes are extended for the period of his service in the combat zone, plus 180 days after his last day in the combat zone. This extension applies to the filing and paying of your son's income taxes that would have been due April 15. In addition to the 180 days, his extension period will include the 46 days that were left before the April 15th deadline when he entered the combat zone. During his 226-day extension period, assessment and collection deadlines will be extended, and he will not be charged interest or penalties attributable to the extension period.
http://www.irs.gov/newsroom/article/0,,id=101265,00.html