First of all, if your tax return is really that simple, you should file it yourself and save the filing fee. The IRS and many other agencies will help you file and answer your questions for free.
If your return is very complicated, your preparer may have given you an “organizer” to fill out. These can be helpful if you have a lot of stock transactions or other circumstances. That’s fine, because your preparer has all the information necessary for you to pay the least amount of tax possible.
If you are in between (and almost everybody is), you should allow the preparer to interview you to be sure that you get all of the deductions and credits you have coming. The few minutes you spend with the tax preparer can yield a payoff of thousands of dollars per hour for the time you are sitting there!
But if you drop it off (and nobody asks) you could miss mortgage deductions, property tax deductions and a lot more. Even if you don’t itemize, there are a lot of “above-the-line” deductions or credits that you could be taking! Sit back and take a few minutes to be sure you are getting the refund you deserve.