The letter from the IRS will provide information about what is the issue that they believe to be incorrect. You should review the IRS letter and compare the issue(s) identified in the letter with the tax return completed in GTP. You should contact the GTP Support Center at support@glaciertax.com – in many cases, the IRS makes a mistake so do not presume that the IRS is correct – GTP will assist you in getting the issue corrected.