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Fort Collins, CO CPA firm

About Williamson & Co. P.C.

CPA Firm for the Real Estate and Construction Industries

Williamson & Co. P.C. is a Fort Collins, CO CPA firm with a fine reputation for accounting and tax planning expertise. We’ve created a specialized niche within our firm for construction and real estate accounting, tax reduction planning, and business advisory. Our experienced team delivers comprehensive service to real estate industry professionals including investors, commercial property managers, architects, engineers, and construction businesses.

As our client, we’ll manage all your essential accounting functions and effectively plan for tax time with innovative strategies designed to significantly reduce taxes. We’ll also provide the financial guidance and direction to minimize risk, increase profitability, and add value to your business. We aim to build a longstanding relationship and deliver excellent service to every client with competence, perseverance, and a personal approach.

To learn more about how our accounting solutions can benefit your business, call 970-482-2272 now or request a consultation online.


Alan WilliamsonAlan has been a CPA since 1993, and earned his MBA and BS in Business Administration after graduating from the University of Colorado. With more than 30 years of financial positions with public and privately held companies his diversified background brings unique perspective to his clients. Alan's goal is to have all of his clients experience our commitment to excellence by providing total financial services to individual and small-to-medium business clients. His emphasis is on early planning incorporated with knowledge based financial strategies and coordinated business and personal planning.


Tammy has been a tax accountant working primarily with small businesses and their owners in several roles since graduating from Colorado State University in 1980 with a BS in Business Administration with a concentration in Accounting. She has worked with the firm since 1988. She enjoys working with a wide variety of small businesses including agricultural business, and appreciates the personal relationships that are built as she works with clients regarding tax compliance, payroll matters, tax planning, Quickbooks systems, entity formation, and estate and trust taxes.

JANICE FOSTER, Staff Accountant

Janice Foster has been in the accounting profession for nearly 20 years.  She earned a B.A. in Economics and B.S. in Accounting.  She has worked in the financial industry working for Merrill Lynch as a registered representative assistant.  Then she moved on to specialize in forensic accounting as a Certified Divorce Financial Analyst.  Janice enjoys all aspects of tax and financial planning, and has extensive experience working with small business, partnerships, trusts and individual tax preparations.  When Janice is not working, her life is full raising her three boys with her husband and enjoying the beautiful outdoor scenic life of her new home, Colorado.


Jeanne joined Williamson & Co. PC as a Tax Accountant in 2018. She graduated from the University of Wyoming with an Accounting Degree in 1990 and has worked in the banking industry and public accounting. She holds a CPA license in both Wyoming and Colorado and has over 10 years of experience in taxation. Jeanne really enjoys having the opportunity to get to know our clients and strives to provide them with excellent customer service.

MONIQUE RIED, Marketing/Client Development Coordinator

Monique is a University of Denver Honor Graduate with a BA in Sociology and Speech Communications with a concentration in mediation/conflict resolution. She went on to hold many different management positions in a variety of industries. Over time she developed a passion for marketing, customer satisfaction, and client development. Monique originally came to Williamson and Company in early 2018, and has held several positions including Payroll Manager, Office Administrator and now Marketing/Client development Coordinator.

TESSA GALLEGOS, Administrative Assistant

Tessa has been with the firm since late 2014. She assists our professional accounting staff by wearing many hats, and by using her exceptional technological savvy. She is a friendly voice and smile with staff and our valued clients. Tessa received her AA in Business Administration from Front Range Community College in 1990. Previously, she worked in private business and government positions in the areas of accounts receivables/payables, payroll, and customer service. Tessa’s skill set adds yet another beneficial and positive dimension to our already stellar administrative support staff.

GAIL MULLEN, Receptionist

Gail recently joined the team at Williamson and Company. She has lived in Fort Collins for 34 years and been in administrative support positions most of her career. She enjoys working with people and making clients feel cared for. Gail, as a long time resident, also believes in being involved in the Fort Collins community.


Brandi began her career in accounting in 2014, and has extensive experience in all aspects of bookkeeping and accounting. She earned a B.A. in Spanish in 2012, and then graduated with a master’s in accounting from Colorado State University in 2018. In her role as a bookkeeper, Brandi takes pride in assuring that all financial aspects of a company are in good hands, including making sure that all client funds are handled ethically and with integrity. She joined Williamson and CO. in 2019 and is excited to use her financial knowledge to help the clients at our firm. In her spare time, Brandi enjoys the beautiful Colorado sunshine, playing at parks and swimming with her young son. She also can't resist curling up with a good book and baking/eating fresh cookies.


  • David Cohen, CPA
  • Iris Fontane, EA
  • Tyler Posing, CPA