Barbara Houston is a CPA with her own accounting and tax practice. One day an audit client asks her to represent him in a conference with the IRS about her prior years' tax return. It seems the IRS is claiming Barbara owes $$50,000$ additional taxes. The client agrees to pay Barbara $20$ percent of the amount of additional taxes saved after the conference with the IRS. What are the ethical issues of concern for Barbara under the AICPA Code and Treasury Circular $230?$