(a) Requirements. A practitioner must not give written advice (including electronic communications) concerning one or more Federal tax issues if the practitioner bases the written advice on unreasonable factual or legal assumptions (including assumptions as to future events), unreasonably relies upon representations, statements, findings or agreements of the taxpayer or any other person, does not consider all relevant facts that the practitioner knows or should know, or, in evaluating a Federal tax issue, takes into account the possibility that a tax return will not be audited, that an issue will not be raised on audit, or that an issue will be resolved through settlement if raised. All facts and circumstances, including the scope of the engagement and the type and specificity of the advice sought by the client will be considered in determining whether a practitioner has failed to comply with this section. In the case of an opinion the practitioner knows or has reason to know will be used or referred to by a person other than the practitioner (or a person who is a member of, associated with, or employed by the practitioner's firm) in promoting, marketing or recommending to one or more taxpayers a partnership or other entity, investment plan or arrangement a significant purpose of which is the avoidance or evasion of any tax imposed by the Internal Revenue Code, the determination of whether a practitioner has failed to comply with this section will be made on the basis of a heightened standard of care because of the greater risk caused by the practitioner's lack of knowledge of the taxpayer's particular circumstances.

(b) Effective date. This section applies to written advice that is rendered after June 20, 2005.