http://www.usataxplanner.com - Mistake spotting and correction. E-filing reduces the risk of mistake in two ways. First of all, as you're entering your information, there are built-in errors ensures features that confirm the correctness of your input, and there's no guesswork as to what applies to what. Secondly, when you mail your return, someone at the IRS has to enter it into their database. There's a risk of error there, that's eliminated when you e-file because the information is already in electronic form.