Castellon Professional Services

Certified Public Accountant

Tax Management Services

At Castellon Professional Services we guide our clients through a full range of tax planning and preparation decisions with strategies that minimize your tax liabilities, maximize your cash flow and keep you on track to your financial goals. Our expertise, experience, analysis and thorough research allow us to optimize financial opportunities to be found in existing as well as recently altered tax laws. We are knowledgeable and up to date on the tax laws and can make sense of your receipts, bills and notices.


Debt and Finance Advising

Whether your needs are corporate or personal, Castellon Professional Services' professionals can assist you in sorting out the different options available for debt management and financing that will lower your payments and/or reduce the total amount of interest paid. Even if you are able to handle the payments and the amounts of your current debts, our expertise may be able to save you money and/or lower your payments.


IRS Representation

Professional representation can be vital during an audit, and our experience with tax authorities enables us to guide clients in their dealings with federal and state agencies. If you have been chosen for an audit, the professional representation you can find with our firm can put many of your worries at bay. We are ready and willing to answer any and all questions the IRS may be asking of you.


Estate and Trust Planning and
Tax Preparation

Effective estate and trust planning can ensure financial security for loved ones. For businesses, it can maintain a smooth succession of ownership. Castellon Professional Services' role is to help you navigate the complex and shifting tax laws to facilitate the transfer of assets and minimize the tax liability of your beneficiaries. Everyone should have a well thought out plan as to how to disburse one's estate so as to avoid complications and to be sure wishes are followed. Having your taxes and estate thoroughly and carefully planned will ensure that your loved ones do not have any complications to deal with during a time of loss.


International Taxation

Our experience with the taxation of U.S companies doing business abroad and residents working abroad as well as foreign corporations doing business in the U.S or foreign citizens working in the U.S., has provided us with an extensive base of knowledge in the area of international taxation.


Cost Segregation Service

Cost Segregation is a stratiegic, tax-saving tool that can be used by companies and individuals who have constructed, purchased, expanded, or remodeled any kind of commercial real estate. Cost segregation allows the owner to take advantage of accelerated depreciation deductions and defer federal and state income taxes.

The result of applying Cost Segregation is that a property owner's tax obligation is reduced and cash flow is increased.

Our team of on-staff specially-trained engineers and strategic engineering partners can provide you with the required forensic study quickly and affordably, regardless of the size or value of your property.


Our Mission

Our mission is to assist clients maintain and improve financial viability in the present, while taking a proactive approach to achieve future goals. This requires open and proactive communication to reach an understanding of our clients' needs through research, sound analysis and strategic consultative problem solving.



For years, Castellon Professional Services has been providing quality, personalized financial guidance to individuals and businesses. Our expertise ranges from basic tax management to strategic financial planning.

By combining our expertise, experience and a consultative attitude, we assure that every client receives close analysis and attention that is vital to producing the best result. Taking the time to know and understand our client's current and future needs means we can make recommendations to take the best course of action among various choices.


Frank Mario Castellon,

Frank Mario Castellon is an accomplished tax consultant with both individuals and entities in the Life Sciences, Hi-Tech and manufacturing industries. He has extensive experience with evaluation, consultation and preparation regarding various tax issues including filing status, itemized deductions, small businesses, sale of personal residence, Offers-in-Compromise, audit representation, collections representation, IRS and state notice response, risk assessment and management and multinational C-corporation tax matters. He is a seasoned consultant with 8 years Big Four and 6 years of industry experience dedicated to assisting individuals and senior management in the decision-making process of determining tax strategies and providing compliance tax services.

Frank Mario Castellon is a certified public accountant (CPA) licensed in California, USA with passing scores in the 87 to 90-percentile range. He graduated summa cum laude from Fresno State University with a BS degree in Business Administration with an option in Accounting. Co-author of three articles published in the AICPA Tax Adviser and Journal Accountancy.

In 2012, Frank Mario Castellon was recognized and awarded by the American Institute of Certified Public Accountants and Chartered Institute of Management Accountants, the world-class designation of Chartered Global Management Accountant. These are two of the worldÂ’s leading accounting organizations recognized and awarded him for the proven ability to combine financial expertise and business acumen to achieve sustainable business success.


Castellon Professional Services

Office (415) 655-6626
Cell (650) 454-0253 
Fax (650) 362-1872

Office Locations:

  • 48 Gold Street, Suite 200, San Francisco, CA 94133
  • 1279 Poplar Ave., No.119, Sunnyvale, CA 94086