Nobody’s perfect, but you should strive to be when it comes to preparing your taxes.

According to the Internal Revenue Service, there were more than 4 million math errors on federal returns last year — and millions more had incomplete or missing information, which can delay the processing of the return and, ultimately, the arrival of a refund, said IRS spokeswoman Kris Moore.

And then there are the simple mistakes — those that make you slap your head and say, “Duh!” Those include not sending all forms and not putting proper postage on the return package.

So before you file that tax return, check out this list of top tax-filing mistakes to avoid.

• Incorrect or missing Social Security numbers. The IRS says this mistake causes more problems than anything else, with more than 1 million returns last year showing up with missing or incorrect numbers. Make sure you double-check the number for yourself, your spouse and any dependents.
• Errors related to the earned income tax credit, which is a tax break that helps low-income workers who may or may not have children. Some who qualify may not even know about it, while others miscalculate what they’re owed. For information on the EITC, visit the IRS Web site at www.irs.gov.
• Incorrect tax table. About 13 percent of all errors fall into this category, Moore said. Thousands of filers compute the wrong amount for taxes owed last year, mainly because they took the wrong number from the tiny tax tables in the back of the 1040 instruction booklet.

“We see that a lot,” Moore said. “We tell people to put a ruler or paper under that line because they can pick up the line above or the line below.”

• Errors involving the child-care tax credit. About 13 percent of errors fall into this category, Moore said, with many filing an incorrect amount or the child is too old to qualify.
• Incorrect refund amount or balance-due amount, which occurs mainly because of math errors, Moore said.
• Taxable amount of Social Security is incorrect or the taxable income is figured incorrectly — again math errors.
• Head of household filing status incorrectly claimed, which often happens when a taxpayer didn’t look at everything required to qualify for head of household, Moore said.
• Not signing or dating the return.
• Forgetting about interest and dividends. Financial institutions report interest and dividend payments to the IRS, and the IRS then cross-checks the information. If you forget to include the information on your return, the IRS will let you know that you owe taxes on it. Absent income also could cost you penalty and interest charges, so make sure you include interest and dividend payments on your return.
• Forgetting to donate charitable items before Dec. 31. The wholesale value of the contributions is allowed as a charitable deduction, but make sure you get a receipt.

Many mistakes can be eliminated by filing electronically, Moore said. Filing electronically, compared with paper filing, is quicker, more accurate, the fastest way to get a refund and the best way to confirm the IRS received your tax return, Moore said.

“The error rate runs 1 percent for filing electronically. It’s very low,” she said. “If you don’t have errors, you won’t be contacted by the IRS, which makes you happy, and it makes us happy because it reduces the amount of work we have to do. By filing electronically, you also get confirmation with the IRS that the return was received, which takes some stress off your shoulders.”