In most cases, the IRS would have notified you in the year you were disallowed. You would have received a notice in the mail. In addition, the refund that you actually received from the IRS would have been less than what was reported on the return that you filed. If you are unsure if you have been previously disallowed for EIC, you would need to contact the IRS at 1-800-829-1040 to find out.