The following excerpt from IRS Pub 15, applies to your situation:
Although the corporation is the primary debtor here, there is a "Trust Recovery Penalty," which may apply if income, social security, and Medicare taxes that must be withheld are not withheld or are not deposited or paid. The penalty is the full amount of the unpaid trust fund tax. If the taxes cannot be collected from the business, the penalty may be imposed on all persons who are determined by the IRS to be responsible for collecting, accounting for, and paying over the taxes, and who acted willfully in not doing so. Any officer, employee, accountant, or anyone who signs checks for the business or otherwise has authority over the spending of the business. "Willfully" means voluntarily, consciously, and intentionally. A responsible persona acts willfully if the person knows the required actions are not taking place.