You can start checking on your refund 24 hours after e-filing or 4 weeks after you have mailed your return. Your refund status is available on https://www.irs.gov/refunds. You will need to provide your social security number or ITIN, filling status and exact refund amount when checking the refund status. All the data you need are shown on your tax return. You can call the IRS if it has been 21 days or more since you e-filed, or 6 weeks or more since you mailed your return. If you lost your refund check, you can initiate a refund trace by calling IRS at 800-829-1954.