Established 1983  ·  Dallas, Texas
Counsel Worthy
of Your Legacy.

For four decades, the names behind Dallas's most consequential tax and financial matters have placed their trust in Thornton James.

William D. Thornton Senior Partner  ·  Founding Member
Our Philosophy

Discretion is not a
service — it is our
first obligation.

"The finest tax counsel is invisible. Our clients sleep soundly because their affairs are in order — not because they are in the news."
— William D. Thornton, Founding Partner

Since 1983, Thornton James LLP has guided Dallas's most distinguished families, private enterprises, and family offices through the full spectrum of tax and financial law. We do not chase headlines. We build enduring relationships grounded in integrity, precision, and an unwavering commitment to our clients' financial futures.

Our attorneys are not generalists. Each brings deep, concentrated expertise to a specific domain of tax and financial law — and together, we bring the full weight of that knowledge to bear on every engagement.

Founded
Dallas, 1983
Structure
Partnership
Focus
Tax & Finance
Reach
National
Areas of Practice

Comprehensive Tax &
Financial Counsel

From strategic tax planning to IRS dispute resolution, our practice encompasses the full range of challenges facing high-net-worth individuals and closely held enterprises.

Strategic Tax Planning

Long-horizon tax strategy designed to compound advantage across generations. We architect structures that minimize liability today while preserving flexibility for tomorrow's business and personal objectives.

Estate & Transfer Tax

Preserving generational wealth demands foresight. Our estate tax counsel integrates seamlessly with your family's existing advisors to engineer transfer strategies that honor both the letter and spirit of your wishes.

Business Succession

The transition of a family enterprise is among the most consequential events in a business's history. We structure the transaction — and the relationships — to ensure the legacy you have built endures on your terms.

IRS Disputes & Audits

When the government calls, composure matters as much as competence. Our seasoned litigators bring decades of negotiation experience to every IRS controversy — protecting your interests at every stage of the administrative and judicial process.

Wealth Preservation

Accumulated wealth requires ongoing stewardship. We design integrated structures — trusts, family limited partnerships, charitable vehicles — that protect assets from exposure while maximizing growth and tax efficiency across the family balance sheet.

M&A Tax Advisory

Every transaction has a tax dimension that shapes its ultimate value. Our M&A tax team structures deal economics from letter of intent through closing — identifying exposures, optimizing consideration, and ensuring the economics reflect the intention.

Four Decades. One Commitment.

Since opening our doors on Commerce Street in 1983, every partner, every associate, every staff member has answered to a single standard: that the client's interest is supreme, their confidence is sacred, and their outcome is our reputation.

Est. 1983

Trusted by Texas's
Most Prominent Families

From oil and gas dynasties to tech founders, multi-generational ranches to family foundations, our client roster reads like a quiet history of Dallas enterprise. We cannot share their names — and that is precisely why they trust us.

42
Years in Practice
18
Partners & Associates
$9B+
Tax Matters Counseled
98%
Client Retention Rate
Top 1%
Best Lawyers in America
Our Attorneys

Depth of Expertise.
Breadth of Experience.

William D. Thornton
Senior Partner · Founder

Estate tax planning, family office structures, multi-generational wealth transfer. Harvard Law, J.D. 1979. Board Certified, Tax Law.

Margaret L. James
Managing Partner

IRS controversy, Tax Court litigation, international tax compliance. Yale Law, J.D. 1985. Former IRS Chief Counsel, Dallas Division.

Robert K. Calloway
Partner, M&A Tax

Mergers, acquisitions, corporate restructuring, private equity tax. SMU Dedman Law, J.D. 1993. LL.M. Taxation, NYU.

Katherine A. Holt
Partner, Wealth Preservation

Asset protection, charitable planning, trust administration, family limited partnerships. UT Law, J.D. 2001. Board Certified, Estate Planning.

Thornton James has represented our family's financial interests for twenty-seven years. Three generations, two estate transitions, and a business sale that spanned eighteen months. They have never once let us down — and they have never once made us feel like a file number.

George & Eleanor Whitfield Third-Generation Dallas Family  ·  Clients Since 1998
Private Consultation

Your first
conversation
costs you nothing.

Initial consultations are conducted in complete confidence. Our attorneys will listen, evaluate your circumstances, and provide a candid assessment — with no obligation and no pressure. We earn your trust before we ask for your business.

Engagements are accepted on a selective basis. We limit our client roster deliberately, so that every client receives the full attention of a senior partner.

Office
2001 Ross Avenue, Suite 4800
Dallas, Texas 75201
Direct Line
(214) 555-0183
Correspondence
counsel@thorntonjamesllp.com
Office Hours
Monday – Friday, 8:00 am – 6:00 pm CST
After-hours by appointment

Request a Consultation

All communications are protected by attorney-client privilege from the moment of first contact.

Your inquiry is protected by attorney-client privilege. We do not share client information. Ever.