IRS Notice CP160 is a "reminder" notice of past due taxes. It is similar in wording & effect as the CP187 & CP163 Usually, these notices involve Form 941, the Employee Withholding form. Although the problem is persistent the IRS is not actively seeking enforced collection. Therefore, you have time to investigate, research & pursue your case.
Respond to Notice CP160
Because these taxes involve Employee Withholding they are not dischargeable in bankruptcy. Plus, the amounts will likely be assessed against all Responsible Persons in the business. Thus, unless the business ceases the IRS has 2 avenues of pursuing the taxes. If the business remains on-going you should coordinate the business liability with the personal liability so the owner & the business are both protected.
The major problem businesses face is that the amount of penalties & interest charged by the IRS is so enormous that the business may have to be closed. You may have to plan on this eventuality. If so, the Responsible Person will have to make other arrangements. But, if the circumstances are good, an Offer in Compromise may be recommended.