Which of the following is NOT considered a non-precedential authority?

The correct choice identifies revenue rulings as a type of authority that is, in fact, considered precedential. Revenue rulings are interpretations of the tax law issued by the IRS that apply to a specific set of facts and provide guidance to taxpayers on how the IRS intends to enforce the law in similar situations. Because they are binding on IRS employees and provide reliable guidance to taxpayers, they qualify as precedential authority.

In contrast, the other options listed—proposed regulations, chief counsel advice, and technical advice memoranda—are generally considered non-precedential. Proposed regulations offer insight into the IRS's future plans but do not have the force of law until finalized. Chief counsel advice is intended for internal IRS guidance and is not for public use, hence lacks precedential effect. Technical advice memoranda are also specific to the facts of a particular case and do not create binding legal precedent.