Mark is a Partner and Co-Founder of Altum Partners, LLP, where he advises venture-backed, private equity-backed, and publicly traded companies on complex corporate tax matters.

With more than two decades of public accounting experience, he specializes in providing strategic tax planning and compliance services to businesses ranging from early-stage startups to mature multinational organizations. His expertise includes income tax provisions and FIN 48 documentation, Section 382 analyses, research and development tax credits, stock compensation, sales and use tax, international tax reporting, mergers and acquisitions, due diligence, and federal and state tax consulting. He is known for helping clients navigate complex technical issues with practical, business-focused solutions that support growth at every stage of a company’s lifecycle.

Throughout his career, Mark has partnered with companies preparing for an IPO or SPAC transaction, expanding internationally, raising capital, or pursuing an acquisition or exit strategy. He works closely with management teams to provide proactive guidance that extends well beyond tax compliance.

Mark earned a Bachelor of Science from California Polytechnic State University, San Luis Obispo, and a Master of Science in Taxation from San Jose State University.

Outside of the office, he enjoys spending time with his family, traveling, and playing golf.

Sara has been an integral member of Altum Partners since 2013 and is a Partner in the firm’s Corporate Tax practice. With nearly two decades of public accounting and industry experience, she advises clients on complex U.S. federal and state corporate tax compliance, tax planning, income tax provisions, and strategic tax matters. Sara works with businesses at every stage of growth from venture-backed start-ups to large, multi-state and multinational corporations with particular expertise in the software, mobile applications, online services, consulting, design, and biotechnology industries.

Sara is known for developing long-term client relationships and serving as a trusted advisor to management teams, founders, and finance executives. She takes a practical, business-minded approach to solving complex tax issues, helping clients navigate changing tax laws while identifying opportunities that support their long-term growth and business objectives. In addition to serving clients, Sara is passionate about mentoring the next generation of tax professionals and fostering a collaborative, client-focused culture within the firm.

Before beginning her public accounting career in 2007, Sara worked for a venture-backed software company specializing in mobile banking. As part of a two-person accounting team, she partnered closely with the CFO and gained firsthand experience in nearly every aspect of the finance function from day-to-day accounting and month-end close to financial reporting, board presentations, employee benefits, and onboarding. That experience gave her a unique understanding of the operational and financial challenges businesses face and continues to shape the practical advice she provides to clients today.

Sara earned her Bachelor of Arts in Mathematics from Occidental College and completed the Certificate of Advanced Accounting Proficiency (CAAP) at Santa Clara University. She is a Certified Public Accountant (CPA) in California and is a member of both the California Society of Certified Public Accountants (CalCPA) and the American Institute of Certified Public Accountants (AICPA).

Outside of the office, Sara enjoys spending time with family and friends, traveling, and cheering on her favorite sports teams.

Stacy is a Founding Partner of Altum Partners and has been practicing public accounting since 2002. With more than two decades of experience, she serves as a trusted tax advisor to companies ranging from emerging start-ups to large, multi-state and multinational public corporations. Stacy is known for combining deep technical expertise with practical, strategic guidance, helping clients navigate complex tax matters while supporting their long-term business objectives.

Her practice focuses on U.S. federal and state corporate tax compliance, tax planning, income tax provisions, and international tax matters. Over the course of her career, Stacy has advised clients on a broad range of technical issues, including mergers and acquisitions, transfer pricing, Section 382 limitation studies, research and development tax credits, stock-based compensation, state and local taxation, income tax audits, and the evolving complexities of multi-state apportionment. She also has significant experience serving limited liability companies and S corporations, allowing her to advise businesses across a variety of entity structures.

Stacy has extensive experience serving technology companies in the software, SaaS, hardware, and biotechnology industries and has guided numerous clients through periods of rapid growth, acquisitions, and initial public offerings. Her ability to understand both the technical tax rules and the operational realities facing growing businesses has made her a valued advisor to founders, finance executives, and management teams alike.

As one of the founding members of Altum Partners, Stacy has played a key role in building the firm’s culture and reputation for technical excellence, responsiveness, and exceptional client service. She is passionate about developing lasting client relationships, mentoring the firm’s professionals, and delivering thoughtful, practical solutions that help clients succeed.

Stacy earned dual Bachelor of Arts degrees in Business Economics (with an emphasis in Accounting) and Communication from the University of California, Santa Barbara, graduating with honors and distinction in her major. She also holds a Master of Science in Taxation from San José State University and is a Certified Public Accountant (CPA) in California. Stacy is a member of both the California Society of Certified Public Accountants (CalCPA) and the American Institute of Certified Public Accountants (AICPA).

Outside of the office, Stacy enjoys spending time with her family, watching and participating in a variety of sports, tackling the occasional craft project, and traveling whenever she has the opportunity.

Ana is a Tax Manager with experience in public accounting, specializing in U.S. federal and state corporate income tax compliance, international tax, tax planning, and income tax provisions. Since entering public accounting in 2018, she has advised clients ranging from emerging start-ups to large multinational companies across industries including SaaS, software, mobile applications, online services, fintech, and biotechnology.

Prior to joining Altum Partners, Ana built more than a decade of accounting experience across a variety of industries, providing her with a strong business perspective that enhances her tax advisory approach.

Ana is a licensed Certified Public Accountant (CPA) in California and holds a Bachelor’s degree in Electronic Engineering, a field she pursued before discovering her passion for tax and accounting.

Outside of work, Ana enjoys spending time with her family, traveling, hiking, and fishing.

Catherine Chalfant is the Director of Tax, Finance & Operations and a Co-Founder of Altum Partners. Since beginning her public accounting career in 2004, she has developed extensive experience advising closely held businesses, investment entities, and high-net-worth individuals on complex tax matters while also helping build and lead the firm’s strategic operations.

From a tax perspective, Catherine specializes in flow-through entities, including S corporations, family real estate partnerships, venture capital and fund-of-funds structures, investment partnerships, and operating partnerships. She also advises clients on tax planning and compliance for high-net-worth individuals and their families, with experience in qualified small business stock (QSBS), equity compensation and stock option planning and multi-state taxation. Her practical, solutions-oriented approach helps clients navigate sophisticated tax issues while supporting their long-term financial and business objectives.

In addition to her client responsibilities, Catherine oversees the firm’s finance, operations, and human resources functions. She is responsible for Altum Partners’ internal financial operations, including budgeting, financial reporting, payroll, tax compliance, and strategic planning, while also leading many of the initiatives that shape the firm’s culture and long-term success.

Catherine has played a key role in designing and implementing the firm’s recruiting, onboarding, training, and professional development programs, creating structured learning paths that support technical excellence and career growth. She also oversees performance management, employee engagement, benefits administration, HR compliance, and operational strategy, helping ensure Altum Partners continues to attract, develop, and retain exceptional talent while maintaining a collaborative and people-focused culture.

As one of the firm’s founders, Catherine has been instrumental in building Altum Partners into a premier boutique corporate tax practice known for its technical expertise, exceptional client service, and investment in its people. She is passionate about mentoring professionals, improving operational efficiency, and creating an environment where both clients and employees can thrive.

Catherine earned her Bachelor of Science in Business Administration with an emphasis in Accounting from Santa Clara University and her Master of Science in Taxation from San José State University. She is a Certified Public Accountant (CPA) and remains actively involved in developing innovative processes and training programs that help the firm stay at the forefront of the profession.

Outside of the office, Catherine enjoys spending time with her family, watching movies, kickboxing, playing volleyball, and sneaking in a well-earned nap whenever she can.

Denise has been a valued member of Altum Partners since 2012 and currently serves as our Accounts Receivable Manager. Throughout her tenure, she has taken on a variety of roles, making her an integral part of the firm’s operations and continued success.

With more than 30 years of managerial and administrative experience in Silicon Valley, Denise began her career after earning her Paralegal Certificate from Sawyer College. She worked in the legal profession before transitioning to the technology sector, where she discovered that her organizational and operational expertise translated seamlessly to public accounting.

Denise has worked in public accounting since 2000, beginning her career at Deloitte alongside one of Altum Partners founding partners Jim Donaldson (retired 2025). Today, she oversees the firm’s billing, collections, and accounts receivable reporting while also providing administrative support across the firm. Her attention to detail, organization, and commitment to client service help keep the firm’s day-to-day operations running efficiently.

Outside of the office, Denise enjoys spending time with her family and friends, reading, relaxing with her pets, and taking long rides on her motorcycle.

Andrew has been an integral part of Altum Partners since 2019, serving as our Office Manager and helping ensure the firm’s day-to-day operations run smoothly. While his professional background is outside of public accounting, Andrew has developed a genuine appreciation for the tax profession and enjoys supporting both our team and our clients behind the scenes.

Before joining Altum Partners, Andrew worked as an Employment Counselor for a government agency, where he gained valuable experience in client service, organization, and problem-solving.

Andrew earned his Bachelor of Arts in Psychology and Communication from the University of California, Davis. Outside the office, he enjoys photography, volunteering in the community, and catching up on sleep on the weekends.

Daniel has been a valued member of Altum Partners since 2017 and currently serves as a Tax Manager. He specializes in U.S. federal and state corporate tax compliance, international tax compliance, tax planning, and income tax provisions for businesses ranging from emerging growth companies to established multinational organizations.

Daniel works closely with clients in the software, mobile applications, online services, and biotechnology industries, helping them navigate complex tax matters while delivering practical, business-focused solutions. He is known for his analytical approach, attention to detail, and commitment to providing responsive, high-quality client service.

Daniel graduated Summa Cum Laude from San José State University with a Bachelor of Science in Business Administration, concentrating in Accounting. Since joining Altum Partners, he has continued to expand his technical expertise while mentoring team members and supporting clients through the evolving tax landscape.

Outside of the office, Daniel enjoys staying active by playing soccer, hiking, and exploring the outdoors.

Rachita has been a valued member of Altum Partners since 2016 and serves as a Tax Manager. She specializes in U.S. federal and state corporate tax compliance, international tax compliance, tax planning, and income tax provisions. Rachita advises clients ranging from emerging growth companies to established businesses, with experience serving organizations in the software, mobile applications, online services, fintech, and consulting industries.

Before joining Altum Partners, Rachita gained valuable public accounting experience in India, providing her with a strong international perspective that complements her work with multinational businesses and cross-border tax matters. She is known for her thoughtful approach, technical expertise, and dedication to helping clients navigate complex tax issues with practical, business-focused solutions.

Rachita holds a Master of Science in Taxation from San José State University and a Master of Commerce from India. She is a member of the California Society of Certified Public Accountants (CalCPA) as well as the Institute of Chartered Accountants of India.

Outside of the office, Rachita enjoys painting, hiking, traveling, and spending time with her family and friends.

Andria is a Senior Tax Manager with over a decade of public accounting experience, specializing in U.S. federal and state corporate tax compliance, tax consulting, and income tax provisions. Since beginning her public accounting career in with us in 2015, she has advised clients at every stage of growth from early-stage start-ups to large multi-state and multinational companies.

Her primary focus is serving clients in the software, mobile application development, and biotechnology industries, where she helps navigate complex tax compliance requirements while providing practical, forward-looking tax planning and advisory services. Known for her collaborative approach and attention to detail, Andria is committed to delivering high-quality client service and developing lasting relationships built on trust and responsiveness.

Andria earned her Bachelor of Arts in Business Management Economics with an Accounting Emphasis from the University of California, Santa Cruz. She is also a member of the California Society of Certified Public Accountants (CalCPA).

Outside of the office, Andria enjoys traveling, spending time at the beach, kayaking, and reading.

Prerna has been practicing public accounting since 2016 and serves as a Tax Manager. She specializes in U.S. federal and state corporate tax compliance, tax consulting, and income tax provisions, advising clients from emerging growth companies to established businesses. Her primary industry experience includes software, mobile application development, and biotechnology, where she helps clients navigate complex tax matters with practical, business-focused solutions.

Prerna is committed to delivering high-quality client service while helping clients meet their compliance obligations.

Prerna is a California licensed Certified Public Accountant (CPA). She holds a Bachelor’s degree in Commerce, an MBA in Finance, and a Master of Science in Taxation from San José State University.

Outside of the office, Prerna enjoys cooking, taking long walks, watching movies, and spending time with her family and friends.

Shelly earned her Bachelor of Business Administration in Accounting from Wichita State University in 2016 and is a Certified Public Accountant (CPA) licensed in the state of Nevada. She combines strong technical expertise with a practical, client-focused approach, helping businesses navigate complex tax issues while delivering thoughtful and effective solutions.

Dedicated to continuous learning and exceptional client service, Shelly enjoys building lasting relationships with clients and staying current with the ever-evolving tax landscape to help them achieve their business goals.

Outside of the office, Shelly enjoys staying active, exploring new destinations, and discovering local coffee shops wherever her travels take her.

Shree is a Senior Tax Manager with more than 15 years of public accounting experience, specializing in U.S. federal and state corporate tax compliance, international tax compliance, tax planning, and income tax provisions. Since beginning her career in corporate taxation in 2008, she has advised clients ranging from early-stage start-ups to large, multi-state, multinational corporations.

Her industry experience spans software, mobile applications, online services, consulting, design, and biotechnology, where she partners with clients to navigate complex tax matters and develop practical, strategic solutions. Prior to focusing exclusively on corporate taxation, Shree gained broad public accounting experience in both India and the United States, providing her with a well-rounded perspective and deep technical foundation.

Shree earned her Bachelor of Accounting with distinction as a university rank holder and completed her professional qualification through the Institute of Chartered Accountants of India (ICAI). She is also a member of the California Society of Certified Public Accountants (CalCPA).

Outside of the office, Shree enjoys reading history books, hiking with friends, and exploring the outdoors.