The other reason you should go through your previous year's tax return is to make sure you don't miss out on any credits or deductions.
"The IRS will let you know if you forget to report income, but they won't let you know if you forget deductions and credits," said Weston.
Last-minute filers are likely to miss these deductions if they rush through the process, said Debbie Freeman, director of tax and financial planning at Peak Financial Advisors in Denver.
Student loan interest: You can deduct the lesser of $2,500 or the amount of interest paid during the year, subject to income phaseouts.
Moving expenses: You moved due to a change in your job and your new workplace is at least 50 miles farther away from your old home versus the distance between your old dwelling and your old workplace.
Property taxes: It's not just your primary home that can qualify, but also your second home and perhaps even your timeshare.
Noncash charitable contributions: Be sure to include your receipts. You'll need to file Form 8283 if your deduction for all noncash gifts over $500.
Contributions to certain tax-advantaged accounts: That includes your health savings account and your individual retirement account.
Finally, if you hurry through your return, you might miss out on the fact that you have to report your nondeductible IRA contributions for the year.
This way, you establish basis in your IRA, and when you start taking distributions in retirement, that portion will come out tax free, said Freeman.