Monica J. Henderson, E.A.

Monica began her tax and accounting career in 1998 in Monterey, California, earning her Enrolled Agent designation (​federally licensed tax professional authorized to represent taxpayers before the IRS and prepare both federal and state tax returns​​)​ in 2002. Monica attended Monterey Peninsula College and Golden Gate University, where she developed a strong foundation in accounting and business that continues to guide her work today.

After moving to Phoenix, she founded North Phoenix Tax and Accounting in 2005. A visit to Payson’s scenic Rim Country inspired a permanent move in 2017, and by 2020, her firm became Copper State Tax & Accounting, reflecting her broader Arizona reach. 
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Known for helping individuals and small businesses achieve financial clarity and confidence, Monica provides personalized, accurate, and long-term guidance. She is passionate about building lasting relationships with her clients, ensuring they feel supported through every stage of their financial journey. Outside of work, she enjoys spending time with her horses, caring for her French Bulldogs, and quilting.

Stephanie “Steph” Tangeman, CPA

​With over 30 years of experience in public and corporate accounting, Stephanie J. Tangeman, CPA, brings exceptional expertise and a client-focused approach to Copper State Tax & Accounting. Licensed in Arizona since 1991, she has served individuals, small businesses, and nonprofits with integrity, accuracy, and personalized care.

Her background includes leadership roles at top firms in Arizona, Iowa, and Illinois, along with her own CPA practice. Stephanie specializes in tax planning, financial analysis, bookkeeping, payroll, and software such as QuickBooks, Lacerte, and CCH Axcess Tax.
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A Saint Ambrose University graduate, she’s excited to return to the Payson area to be near family and continue helping clients achieve lasting financial success.

Amy Bookout, Tax Preparer

​Amy Bookout has been a professional tax preparer since 2005, beginning her career at a small accounting firm in the Valley. In 2022, she relocated to the beautiful mountain community of Payson, where she continues to serve clients with dedication and care.

Amy values the relationships she builds through her work and looks forward to supporting both long-time and new clients for many years to come. Outside the office, she enjoys spending time outdoors and cherishing every moment with her husband, children, and grandchildren.