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Karin Langwasser, CPA

Founding Partner in Charge



Karin Langwasser founded Langwasser & Company CPAs in 1989 and has served as the partner in charge of the organization since its inception. She has built the company on referrals from satisfied clients who appreciate her specialization in work with high net-worth individuals with complex business structures to optimize tax efficiency and maximize asset protection. 

Leading one of the Inland Empire’s top recognized full-service accounting firms in Southern California and the United States, Langwasser has been a licensed professional Certified Public Accountant for more than 27 years. In addition to her CPA license, she also holds three other active licenses in a variety of financial fields.

Karin holds Financial Industry Regulatory Authority Series 7 (General Securities Representative) and Series 66 Registered Representative and Registered Investment Advisor) licenses. She also has licenses as a California Registered Insurance Producer (Accident and Health Agent, Life-Only Agent, Variable Contracts Agent).  

Throughout her career, Karin has helped business owners, entrepreneurs and start-up companies create successful business strategies. She leads the company with a results-focused approach, both with clients and employees, to ensure professional and personalized service. Her strategic and efficient tax and accounting processes provide clients with one-on-one attention and custom-tailored solutions to manage, save and protect their money. Using state of the art accounting software and technology, Karin manages thousands of clients’ tax and financial well-being every year providing them with secure and convenient ways to review and approve of their tax returns, no matter where on the globe they may be.

Karin takes a results-oriented approach to client needs, and provides them with expert advice regarding tax planning, accounting, estate planning, and retirement planning* across multiple industries. She routinely assists clients with:

‚Äč                        1031 Exchanges

                        Business Buy-Sell Agreements and Strategy

                        1202 Tax Free Stock Sales

                        Tax Free Corporate Restructuring

                        Divorce Planning



                        Creative Financing Options with Lenders in residential and commercial real estate

                        Development of Tax Reduction Strategies

She is a member of the American Institute of Certified Public Accountants and the California Society of Certified Public Accountants, as well as a graduate of Point Loma Nazarene University. Karin has been an active member of her community for many years and was awarded the Soroptimist Woman of the Year Award and the Ontario Host Lions Club Lion of the Year. She is a former board member of the Pomona Valley Habitat for Humanity and Carden Arbor View School in Upland.

IMPORTANT: Ms. Langwasser’s Series 7 and Series 66 registrations are not related to or required for her business with Langwasser & Company, CPAs or in any way associated with her capacity as a Certified Public Accountant.  

Separately and apart from her business with Langwasser & Company, CPAs and as a Certified Public Accountant, Karin K. Langwasser, through the Trusted Advisors® program of Equitable Advisors, LLC and Equitable Network, LLC, which are affiliated companies and do not provide tax or accounting advice services, offers securities through Equitable Advisors, LLC (NY, NY 212-314-4600), member FINRA, SIPC (Equitable Financial Advisors in MI & TN), offers investment advisory products and services through Equitable Advisors, LLC, an SEC-registered investment advisor, and offers fixed and variable annuity and insurance products through Equitable Network, LLC, which conducts business in California as Equitable Network Insurance Agency of California, LLC.  Langwasser & Company, CPAs is not owned by, operated by, and does not conduct or solicit the business of, Equitable Advisors, LLC or its affiliates.

Registered representatives and insurance agents may transact business, which includes offering products and services and/or responding to inquiries, only in state(s) in which they are properly registered and/or licensed. For more information about Equitable Advisors, LLC you may visit to review the firm’s Relationship Summary For Retail Investors and General Conflicts of Interest Disclosure. 



Cindy Agostini, USTCP, EA, MBA

Managing Partner 


Cindy Agostini is Managing Partner Langwasser & Company CPAs in Upland, California. She has been a partner with the firm since 2017 after joining the company in 2012 as manager of tax.

With more than 20 years of experience in business management, human resources consulting, financial services and tax preparation, Cindy manages the firm’s day-to-day accounting and tax practice operations, helping Langwasser & Company grow more than 18 percent every year for the past five years.

Cindy is uniquely qualified to represent clients before various taxing authorities. As a licensed Enrolled Agent, Cindy is an expert in accounting, tax, tax resolution, audit representation, appeals and tax court representation.  She was admitted to practice as a member of the Bar of the U.S. Tax Court in 2017, a distinction held by fewer than 100 tax professionals nationwide. As a United States Tax Court Practitioner, she is licensed to represent individuals or corporations in the U.S. Tax Court in a capacity of legal counsel.

Cindy has worked to achieve successful audit results involving different agencies such as the Employment Development Department (EDD) of California, the Internal Revenue Service (IRS), and the California Department of Tax and Fee Administration (CDTFA). Her recent victories include:

  • Achieved several ‘no change’ audits on a personal service S Corporations audited by the EDD for reasonable officer compensation and potential worker reclassification of independent contractors.
  • Achieved an Offer in Compromise for a client the IRS had cast doubt as to liability, saving the client $100,000. The IRS accepted this offer with full discharge of liability.
  • Achieved an Offer in Compromise for a client who IRS cast doubt as to collectability, saving the client $380,000.
  • Achieved ‘no change’ audits for clients across industries such as construction, real estate, and manufacturing. Notably, she represented the largest Kickstarter Campaign that was audited by the IRS and achieved a ‘no change’ audit result.
  • Achieved release from IRS garnishment collection for an employee.


Cindy also works closely with business startups, advising clients on tax and accounting requirements relating to new business ventures. She focuses on developing an environment of success for her clients while identifying future challenges and issues.

Throughout her career, Agostini has held top managerial roles for a diverse array of multi-million-dollar corporations in the aerospace and consumer goods manufacturing industries, including Mag Instrument Inc. in Ontario and Weber Aircraft Inc. in Fullerton.

Cindy earned her Master of Business Administration from the University of La Verne and her bachelor’s degree in business administration from Point Loma Nazarene University in San Diego.

An Innocent Spouse Victory When the Taxpayer Knew the Tax Would Not Be Paid, by Cindy Agostini (EA Journal Nov.-Dec. 2021)


Shawn Hull, CPA



Shawn Hull joined Langwasser & Company CPAs in 2012.

Raised in an Inland Empire family of small business owners, Shawn specializes in tax strategy and planning, with a primary focus on “flow through entity” structures as well as corporations. She represents a variety of closely held businesses and high net-worth individuals, with strong concentration in the areas of construction, insurance, media and entertainment, logistics, medical services, manufacturing and distributions, real estate, service-based businesses, technology and startups. 

Shawn has extensive experience in tax authority audits and has represented clients in various cases before the IRS, EDD, U.S. Department of Labor, and California Department of Tax and Fee Administration. She has consulted on a variety of complex tax matters involving capital gains strategy, 1031 exchanges, debt restructuring, business investments, entity selection and structuring, bonding requirements, small business stock exclusion, stock options and business tax credits.

A Certified Public Accountant, she is a member of the American Institute of Certified Public Accountants and the California Society of Certified Public Accountants. She also is a QuickBooks Certified Pro Advisor.

Hull, who lives in Chino Hills, previously was the chief financial officer for a successful well-established construction firm in Riverside.

Shawn earned a Bachelor of Science degree in business administration – accounting from the University of California, Riverside.


Rosa Huerta, CPA



Upland resident Rosa Huerta joined Langwasser & Company CPAs in 2012, promoting from staff accountant to manager of tax and accounting.

With extensive experience in tax planning, accounting and audit and advisory services, Rosa services high net-worth individuals and their families, closely held businesses, trusts and exempt organizations. She also provides tax services for estates and trusts as well as private businesses.

A Certified Public Accountant, Rosa plays an integral role in the development of the firm’s audit and review practice to ensure that all engagements are performed in accordance with professional standards.

She represents a wide variety of clients covering a diverse array of industries, including construction, equipment rental, food and beverage, homeowners’ associations, manufacturing, medical professionals, nonprofit, real estate, wholesale/retail, non-profits, legal services and other service-based businesses.

Rosa is a member of the American Institute of Certified Public Accountants and the California Society of Certified Public Accountants. Prior to joining Langwasser & Company, she was a payroll auditor with Northwest Administrators Inc. in Pasadena.

Huerta holds Bachelor of Science degrees in accounting and Spanish from Loyola Marymount University in Los Angeles.