Tax season began on Jan. 28, but millions of Americans have likely put off filing until the last few weeks before the April 15 deadline.

Government cutbacks over the past few years resulted in a number of layoffs at the Internal Revenue Service. Likely as a result, the number of income tax audits has been falling for years. Still, some 1 million Americans are likely to be audited this year. These audits do not include filers who had their returns sent back to be corrected — often due to extremely simple and preventable mistakes.

There are a number of common pitfalls and surprises to avoid during tax season. The IRS lists several common errors filers make each year on its website. The errors vary in complexity from failing to correctly calculate a deduction on a 1090A form to simply failing to sign and date the return, or even using the wrong postage. While some of these mistakes seem obvious and easily avoidable, they are common enough that the IRS lists them as issues.

A great many of these errors can be avoided simply by filing electronically, as most Americans now do. The number and share of Americans filing electronically rose from just over half of filers in 2005 to over 90% today. Still, filing through a software such as TurboTax or using a service that e-files for you can be expensive, and some prefer the sense of control that filing by hand can provide. Electronic filing also can also prevent filers from including written explanations for certain deductions.

Even when e-filing, many of the mistakes the IRS lists remain common. Many of these can be lumped into the category of, simply, failing to fill in the right boxes or the correct figures, or forgetting to include the various deductions, credits, and allowances. Avoiding these mistakes can help ensure getting your refund without the hassle.

Click here to see the 19 most common tax mistakes