For those of you who wait until the last minute to file your taxes -- which this year are due by Tuesday, April 17 -- here are some tips to make sure you send your returns on time: Filing paper returns on time 1. Postal mail. Your paper return is filed on time if it is mailed in an envelope that is properly addressed, has enough postage, and is postmarked by April 17. The post office keeps many of its offices open until midnight on tax day so returns can be postmarked by this date. If your envelope is lost by the post office or Internal Revenue Service, you'll have no way to prove it was mailed. This is why it is always a good idea to send in a paper return by registered mail or certified mail. This costs more than regular postage, but is well worth it. If you send your return...