IRS Notice CP187 is another "reminder notice from the IRS, similar in effect as the CP160 & CP163. These notices usually involve Form 941 for Employee Withholding Taxes. This can be a persistent problem but the IRS is not actively seeking enforcement so you have time to attack this problem. You need to investigate the various avenues of relief.
Respond to Notice CP187
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.
Often, the amount of penalties & interest charged by the IRS is so high the business is forced to close. Then, the Responsible Person will have to make separate arrangements with the IRS. If the circumstances are good, an Offer in Compromise may be recommended.
So, whether the business plans to stay open or close, mutually exclusive plans must be made to reverse this IRS problem. If it is possible to pay the taxes then those plans must be followed. If the taxes cannot realistically be paid, other arrangements will have to be made.