Usually, the first step the IRS takes is to send you a letter if they have questions regarding your account.
If you ignore this correspondence, it will not go away. The IRS will asses tax, penalties, and interest based on information they have, whether it is correct or not and may exercise their right to a lien or levy to protect their interest.
If you are sent a letter requesting an audit, we recommend you contact us immediately. You have a right to representation. Don't allow yourself to be at an unfair advantage with the IRS auditor whose job it is to deal with audits on a daily basis.