Helping Oklahoma businesses build stronger futures.
Hann Plummer, PLLC partners with business owners through every stage of growth — from startup to succession — with proactive tax planning, financial strategy, and trusted advisory. We're the advisors Oklahoma business owners call before making their biggest financial decisions.
Meet William Hann
For nearly two decades, William Hann has been the trusted advisor Enid business owners turn to when the stakes are highest. He isn't simply someone's CPA — he's a partner in the growth of their business, someone they know personally and rely on for guidance far beyond tax season.
With more than 25 years of accounting experience and a deep understanding of Oklahoma's agriculture, oil & gas, and small business communities, William brings clarity to complex decisions and a steady hand to every stage of a business's journey.
Meet Dee Plummer
Dee Plummer brings something rare to a CPA firm: the perspective of an executive who has actually led businesses from the inside. As a former Controller and Chief Financial Officer, he has sat in the seat our clients sit in — making the calls that shape a company's future.
That operational depth means Dee doesn't just report the numbers — he understands what they mean for growth, cash flow, and long-term strategy. Together, William and Dee form an executive advisory team that helps Oklahoma business owners think bigger and decide with confidence.
We're invested in your business because your success becomes our success.
Hann Plummer isn't simply hired to prepare taxes. Our clients rely on us as the first call they make before the decisions that shape their businesses and families.
Built around people — not accounting services.
Whether you're leading a growing company, running a family farm, or planning for the next generation, you'll recognize yourself here — and find advisors who understand exactly what you're navigating.
- Business consulting
- Payroll
- Accounting
- Growth strategy
- Tax planning
- Entity planning
- Financial management
- Succession
- Tax planning
- Estate guidance
- Life transitions
- Financial confidence
Built for Oklahoma Agriculture
Agriculture is more than an industry here — it's a way of life, and one of the areas where our expertise runs deepest. Few firms understand the rhythms of farming, ranching, and grain operations the way we do.
From volatile commodity cycles to generational succession, we help agricultural families protect what they've built and plan confidently for what's next.
Organized around outcomes.
Not a menu of line items — a set of outcomes that move your business and family forward.
Growth is a decision. We help you structure it, fund it, and lead it with financial clarity.
- Business consulting
- Transaction structuring
- Part-Time CFO
- Financial planning
The right foundation keeps more of what you earn and safeguards your business and family.
- Tax planning
- Tax preparation
- Payroll
- Accounting & bookkeeping
When the stakes rise, you need advisors who can guide you through with confidence.
- IRS representation
- Tax consulting
- Business advisory
- Strategic planning
What working together looks like.
A relationship, not a transaction — designed to support you through every stage of your business.
We start by understanding your business, your goals, and the decisions ahead.
A clear-eyed look at where you stand — books, taxes, structure, and cash flow.
A proactive plan built around growth, protection, and long-term outcomes.
We put the plan to work — cleanly, accurately, and on time.
Ongoing guidance so you're never facing a big decision alone.
Guidance worth keeping.
Educational insights to help Oklahoma business owners make smarter, more confident financial decisions all year long.
Frameworks for building and scaling a resilient Oklahoma business.
What changing tax law means for owners, families, and farms.
Managing cash flow and risk through commodity and weather cycles.
Practical strategies to keep your business liquid and growing.
Getting payroll right — compliance, timing, and peace of mind.
Entity choice, structure, and the financial foundations of a new venture.
State-specific insights for businesses operating in Oklahoma.
Passing the business to the next generation with confidence.
Where Oklahoma business owners turn for trusted guidance.
Our office on East Randolph is more than a place to file taxes — it's where entrepreneurs, families, and agricultural operations come to think through their biggest financial decisions. We'd be glad to meet you.
Schedule a consultation
Tell us a little about your business and what's ahead. William, Dee, and the team will follow up to find a time to talk.