Who said the check was mailed? Did the IRS refund site say your check was mailed? The IRS refund site is the only source of information about your refund. If they really mailed it, then watch your mailbox. They mail it first class mail without any tracking, so no one can tell you how long it will take the US Postal Service to deliver it to your mailbox. Seven to ten business days is the average time it can take for mail to reach your mailbox. Open all mail, even if it looks like junk mail. And double check to make sure you entered the correct mailing address on your tax return.