Recently the IRS came forward with an amnesty program for workers who improperly classify their employees as contractors. There are a number of issues in considering the program. These include the interplay between the IRS and the Department of Labor, the effect such an amnesty agreement would have on your business going forward, and whether the business actually misclassified its contractors.
The Proactive Employer podcast considered the issue recently. I would recommend that discussion as a starting point for anyone considering this issue. It is complex and can have fairly significant ramifications. Please consult with an attorney before you make a decision one way or the other as to proceeding.