This year, American taxpayers got a few extra days to file their 2010 income tax reports. But for procrastinators, the time has come. Every taxpayer must electronically send or mail their personal 1040s by midnight tonight.

For all those last-minute filers, here are some tips to remember as the April 18 deadline fast approaches:

File electronically. Commercial software packages and on-line tax prep sites are still available—with some websites still offering free tax preparation and filing to the IRS. The best thing about filing electronically at the last minute: You won’t have to hunt down a local post office that’s still open at midnight tonight.

Check and double-check your return. Electronic tax prep can help avoid math errors in your return. Still, you have to avoid common errors such as inputting an incorrect Social Security number, address or filing status. And if you're filing by mail, don't forget to sign your paper-based Form 1040!

Have all your paperwork. If you’re going to the post office tonight, make sure you're including all the other forms and schedules— for example, your W-2s and additional schedules, such as Form 1040 Schedule A for itemized deductions and D for capital gains and losses—required for your particular return. (Again, filing electronically simplifies all this paperwork.)

Make copies. Some financial institutions sent their 1099s late this year. So, make sure you have copies of everything you sent to the IRS tonight in case you have to file an amended return later.

Mail it correctly. If you’re filing a paper-based income tax report, make sure you check the IRS’ website for the correct address. Mail your return with the proper amount of postage. (The IRS and U.S. Postal Service recommends sending your return by Certified Mail, but First Class mail with proof of delivery is fine also.)

If you still need more time to file your 2010 personal income tax report, file a Form 4868. The extension to file will give you six more months to prepare your return. But remember, if you think you owe the federal government money, you’ll also need to send an estimated payment with your Form 4868 to avoid penalties for filing past tonight’s deadline.

Avoid Common Mistakes When Filing Your Tax Return [IRS]
IRS Reminds Taxpayers to Mail Returns to the Correct Address [IRS]
IRS offers tips to avoid mistakes on deadline day [Reuters]
9 Last-Minute Tax Filing Pitfalls to Avoid [NASDAQ]