April 15th is coming up quickly, and many of us haven't finished our taxes yet. There are several provisions of the tax law that allow for extensions of time to file for military members.
First, members of the military serving outside the United States (and Puerto Rico) but are not in a combat zone have until June 15th to file your income tax return without penalty. If you owe taxes, however, you will be charged interest from the April 15th due date. You do not need to notify the IRS that you plan to use this benefit, but if you expect that you will owe taxes, you may want to file Form 4868 to pay the estimated amount due and keep the amount of interest charged down. You can also use Form 4868 to request a further extension until October 15th. When you file your returns, make sure to include a statement explaining that you are serving outside the US so that you aren't accidentally penalized for filing after the regular April 15th deadline.
Second, if you are serving in an area that authorizes you hazardous duty/imminent danger pay (officially called a combat zone by the IRS,) your are granted an extension that equals that time that you remain in the combat zone, plus 180 days, plus the time before filing that still existed before you entered the combat zone. This last part is a little tricky, but basically if you entered the combat zone on April 10th, you would get that 5 days included in your extension. (from April 10th to the regular April 15th due date.) The best part about this rule is that you will not be charged any interest or penalities. It is lovely that you can just not worry about your tax return while you are busy serving. The exemption from penalties and interest applies to both spouses as long as you are filing a joint return. There are also provisions for military members who are hospitalized due to injuries received in a combat zone.
All this information, plus more, is included in IRS Publication 3: Armed Forces Tax Guide.
Keep in mind, every state has its own rules and they may or may not be the same as the federal rules. Check with your individual state tax office to make sure you meet their deadlines.