Ontario, CA
Tax & Business Law Solutions

Your Ontario Tax Attorney for Businesses and Individuals
We’re committed to helping Ontario residents resolve their tax controversies, navigate audits, address notices, and plan for business success, all with the personal attention and local knowledge that make the difference.
Comprehensive Tax Law & Business Legal Services in Ontario
Audit Representation
Whether you’re facing an IRS audit or a California state tax review, the outcome can have a major impact on your financial future. Our attorneys defend Ontario clients at every stage, aiming to resolve matters early and minimize exposure to additional taxes, interest, and penalties. Learn about IRS audit defense.
IRS Notice Response & Tax Bill Defense
Receiving an IRS or FTB notice in Ontario? Ignoring it can escalate the problem. We respond promptly, analyze your situation, and provide strategies including payment plans, penalty abatement, and more. Help with IRS notices.
Offer in Compromise & Penalty Abatement
If your tax debt is unmanageable, you may qualify for an Offer in Compromise (OIC) to settle for less, or for penalty abatement to reduce or eliminate certain penalties. We negotiate with the IRS and FTB on your behalf, helping Ontario clients get a fresh start. OIC & penalty abatement services.
Payroll Tax & Trust Fund Recovery Penalty Defense
Ontario businesses are often targeted for payroll tax enforcement. We defend owners, officers, and bookkeepers from IRS and EDD payroll tax claims and Trust Fund Recovery Penalty assessments—minimizing risk and protecting your business and personal assets.
Unfiled Tax Returns & Voluntary Disclosure
If you’ve fallen behind on tax filings, voluntary disclosure may help avoid criminal charges and limit penalties. We guide Ontario clients through every step, negotiating manageable solutions. Resolve unfiled taxes.
State & Local Tax: FTB & CDTFA Defense
FTB and CDTFA (sales & use tax) matters are frequent in California. We provide audit defense, payment plan negotiations, and appeals for Ontario businesses.
IRS Criminal Tax Defense
Facing allegations of tax fraud or evasion? You need aggressive and experienced representation. We defend Ontario clients against IRS criminal investigations, protecting your rights and reputation. More on criminal tax defense.
Innocent Spouse Relief
If your spouse or ex-spouse’s tax actions left you responsible for tax debts, we can help pursue innocent spouse relief to protect your financial well-being. Learn about innocent spouse relief.
Liens, Levies & Garnishments
IRS and California agencies may use liens, levies, or wage garnishments to collect tax debt. We fight to stop aggressive collections, negotiate releases, and restore your financial stability. Liens and levies info.
Back Tax Resolution
Owing back taxes can be stressful and costly. We have successfully resolved over $50 million in tax controversies for our clients. Let us help you take control of your tax debt. Back tax services.
Employee Retention Tax Credit (ERTC) Eligibility
Ontario employers may still qualify for valuable ERTC refunds. We determine eligibility, prepare documentation, and maximize your claim. ERTC details.
Research & Development (R&D) Tax Credits
Many Inland Empire and Ontario-area businesses are eligible for lucrative R&D credits. We help you document and secure these credits, fueling growth and innovation. R&D credit info.
Corporate Transparency Act (CTA) Compliance
The new Corporate Transparency Act (CTA) requires many businesses to report ownership information. We ensure Ontario businesses comply and avoid harsh penalties. CTA compliance.
Estate & Gift Tax Planning
Secure your family’s future with smart estate and gift tax strategies. Our Ontario attorneys help minimize tax burdens and protect wealth across generations. Estate planning services.
International Tax Compliance: FBAR & FATCA
Own foreign accounts or assets? We help Ontario clients navigate FBAR, FATCA, and other complex international tax filings, reducing risk and ensuring compliance. International tax help.
Remote Work, Gig Economy & Digital Asset Tax
Remote work and digital assets bring unique tax issues. We advise Ontario freelancers, consultants, gig workers, and crypto investors on compliance, deductions, and audits. Remote work tax planning.
Not-for-Profit & Charitable Organization Tax Law
We guide local nonprofits through entity formation, 501(c)(3) applications, audit defense, and ongoing compliance. Nonprofit services.
Business Succession, Exit Planning & Asset Protection
Our firm advises Ontario businesses on succession, exit strategies, mergers, dissolutions, and asset protection—helping you plan for the future and reduce risks.
Business Formation & Transactions for Ontario Entrepreneurs
Launching or growing your business in Ontario? We help you choose and form the best entity—C Corporation (learn more), S Corporation (learn more), or LLC (learn more)—with all documentation, strategy, and compliance handled from start to finish. Business formation guidance.
We also represent buyers, sellers, and partners in business sales, mergers, and acquisitions—ensuring you meet all legal and tax requirements and avoid costly errors. Buy or sell a business.


Why Work With The Law Office of Pietro Canestrelli in Ontario, CA?
- 20+ years of tax and business law experience
- Local Inland Empire and San Bernardino County knowledge
- Personalized strategies for every case
- Fast response to IRS and state matters
- Direct attorney access and frequent updates
- Solutions for individuals, families, businesses, and nonprofits
Serving All of Ontario & the Inland Empire
We proudly serve clients throughout Ontario—including Ontario Ranch, Downtown Ontario, South Ontario, Upland, Chino, Rancho Cucamonga, and all neighboring Inland Empire communities
Frequently Asked Questions (FAQs) – Ontario Tax Attorney
What should I do if I get a tax audit or IRS notice in Ontario?
Contact us immediately. Fast action can prevent escalation, reduce penalties, and protect your rights. More on IRS notices.
Can you help with payroll and business tax problems?
What if I owe several years of back taxes or haven’t filed?
We regularly help clients resolve years of back taxes and get back into compliance. Help with unfiled taxes.