Tax Partner - UHNW (Orange County)

Job Summary:

At Mercer Advisors, our purpose is to amplify and simplify our clients’ financial lives through a fully integrated family office offering. We bring together fiduciary professionals across disciplines to do the best work of their careers—as one unified team committed to doing what’s right for clients. We continue to reinvest in our people and platform so that our growth creates more opportunities for teammates and more value for clients.

Regis is Mercer Advisors’ offer designed for ultra-high net worth families with complex, multi-generational wealth. Regis clients often have the means to build their own family office, and they require a deeply integrated wealth management experience with the highest level of service, coordination, and sophistication. We are a team of world-class fiduciary professionals delivering holistic advice across investments, financial planning, estate strategy, tax strategy, and more with the aim of making every client feel like our only client.

We are seeking an exceptional Tax Partner - Regis - to serve as the lead tax advisor, strategist, and subject matter expert for our Regis families. You will lead engagements alongside senior wealth advisors and other Regis team members, with direct accountability for the tax outcomes and experience of our most complex families. This is not a support or review role—you will bring the credibility, judgment, and gravitas that UHNW families expect from their most trusted advisors.

Essential Job Functions for this role include:

• Serve as the lead tax advisor and primary point of accountability for a select group of Regis families, maintaining and growing a book of clients with balance sheets that often exceed +$100M.
• Build practical, year-round, and multi-year tax strategies tailored to each family’s goals, ownership structures, businesses, trusts, investments, charitable activities, and succession plans.
• Lead and develop a select team of UHNW-focused tax professionals supporting Regis engagements, overseeing staffing, engagement economics, billing, and service quality.
• Identify planning opportunities and risks arising from business transactions, concentrated positions, real estate, carried interests, equity compensation, major charitable gifts, residency changes, and cross-border exposure (foreign trusts, PFICs, GILTI, FATCA/FBAR) bringing in specialists when the issue calls for deeper expertise.
• Oversee tax compliance at a level appropriate to each engagement: directly, when Mercer prepares the returns, or through active review and coordination when a family’s own CPA firm or internal tax team handles preparation.
• Lead the response to significant federal and state tax notices, examinations, and controversy matters, coordinating with counsel and other specialists through resolution.
• Partners with Regis wealth advisors and Mercer’s broader team — estate planning, investments, financial planning, and family office services — so tax advice is fully integrated with each family’s overall plan.
• When relevant, collaborate and coordinate the tax calendar / division of responsibilities with the families outside CPAs, attorneys, trustees, investment bankers, valuation professionals, controllers, and other advisors
• Support new client development through prospective client meetings and partner with Regis leadership to evolve the tax service model, team, and technology.

Knowledge, Skills, and Abilities:

• CPA license required; advanced degree in taxation (MST/LL.M.), law degree, or comparable technical credential strongly preferred.
• 12–15+ years of progressive tax experience, with the majority spent advising clients with balance sheets of $25M or greater; meaningful experience with $100M+ families required.
• Deep technical command of individual, fiduciary, partnership, corporate, estate, gift, and state and local taxation, including advanced planning strategies commonly used by ultra-high net worth families.
• Experience identifying cross-border tax and reporting issues and working effectively with international tax specialists; direct technical expertise in every international area is not required.
• Experience managing significant tax notices, examinations, and controversy matters, including coordination with tax counsel.
• Meaningful experience advising entrepreneurs, business owners, executives, and multi-generational families through liquidity events, business succession, wealth transfer, and other significant transactions.
• Ability to analyze complex facts, focus on what matters, and deliver clear, practical recommendations — with excellent written and verbal communication skills to explain sophisticated tax matters in plain language.
• Demonstrated ability to lead and develop high-performing tax professionals and build a culture of accountability and technical excellence.
• Comfort operating in a team-based, integrated advisory environment within a regulated RIA structure; experience at a family office, multi-family office, wealth management firm, or national accounting firm strongly preferred.
• Unquestioned integrity and a strong commitment to confidentiality, sound risk management, and putting the client’s interests first.
• Ability to travel up to 10%.

Work Schedule:

This professional role requires availability during standard business hours of Monday through Friday from 8AM to 5PM.  At times, the role may have early or late hours to meet business tasks and deadlines for external and internal client needs.    

All roles classified as a non-exempt are required to record working time into the timekeeping system daily at the start and end of each workday plus a 30-minute unpaid lunch period.

Working Conditions:

This position may be in a professional office environment or a dedicated home office workspace which is free of interruptions.  Whether position is in a dedicated office space or home office workspace, basic technology needs will be provided to satisfy position requirements.  Routinely sitting and standing for periods of time. No heavy lifting over 10 lbs.