When preparing paper returns, review all math for accuracy. Or file electronically; the software does the math for you.
Take your time. Many taxpayers make mistakes when figuring their taxable income, withholding and estimated tax payments, Earned Income Tax Credit, Standard Deduction for age 65 or over or blind, the taxable amount of Social Security benefits and the Child and Dependent Care Credit.
Double-check your bank routing and account numbers if you are using direct deposit for your refund.
An unsigned tax return is like an unsigned check — it is invalid. Also, both spouses must sign a joint return.
If you file electronically, you must sign the return electronically using a Personal Identification Number. To verify your identity, the software will prompt you to enter your AGI from your 2010 federal income tax return or last year's PIN if you e-filed. Taxpayers should not use an AGI amount from an amended return, Form 1040X, or a math-error correction made by the IRS.