Did you double-check your numbers to see if there was a mistake in your routing or bank account number?
You can verify your banking information by reviewing your printed tax return and confirming the bank information you provided. This will be found on your Form 1040 under the Refund section (Lines 35b and 35d). If there was a mistake in the direct deposit information and the deposit was rejected, the government will mail your refund check to the address on your tax return. For more information, please see What if I entered the wrong bank account for direct deposit?