Employment Tax Treatment

Does a caregiver for an aged chairman have a jurisdiction to carry over fees (salary or hourly) as well as amass arbitrary fees in order to be paid as a present (tax free) during a later date?(such as in a certitude as well as paid during TOD) Who is ultimately obliged for unfiled/unpaid self practice tax... a POA, profession for estate, a EP or a worker who neglects to file self practice to begin with?  Will a IRS reason a estate obliged if owed taxes are not paid or go after a particular who warranted a money?? In this case a POA is also a main caregiver.