If you’re already filed your tax return, you likely have one important question: Where’s my refund?

The IRS, once again, has an app for that. The agency's popular Where's My Refund website tool is back for 2013, with a few improvements. Last year, you could get an estimate of when you could expect your refund. This year, the tool will tell you the date your tax return was received, the date your refund was approved and the date the check was sent or the funds were transferred to your bank. From that point, it’s up to the financial institution and the U.S. Postal Service how quickly you’ll receive your money.

IRS tool helps you track your tax refund. © Steve Allen-Brand X-Corbis
If you file electronically, you should be able to start tracking the status of your refund within 24 hours. If you file a paper return, you will have to wait three to four weeks. You can also track your refund on iPhone or Android using the IRS2Go smartphone app.

The IRS says you can expect your refund within 21 days of filing your return electronically, with a longer wait if you file on paper. Last year, the agency notes, 90% of refunds were issued within that time frame, and the same performance is expected this year.

To check the status of your refund, you will need to enter your Social Security number, your filing status (single, married, etc.) and the exact amount of your refund from your tax return. If you filed a joint return, you can use either Social Security number to check. If you file an amended return, you cannot use this tool to track your refund.

The information is updated every 24 hours, usually overnight, so you need to check only once a day.

You can get more information from the IRS' Frequently Asked Questions page on refunds and from the "When Will I get My Refund" video on YouTube, one of 130 informational videos the agency has posted.

More from MSN Money: