Lehman Accounting Group was founded in 2025 by Mark and Jeff Lehman, a father-son team with one clear mission: deliver Big 4 expertise and sophistication to small and medium-sized businesses with the warmth, responsiveness, and trust of a family-owned firm. Jeff spent years at a Big 4 accounting firm, honing the technical precision, proactive planning, and high-touch service that large corporations take for granted. He saw an opportunity to bring that same level of quality to Main Street businesses that are too often overlooked or overcharged by larger firms. Partnering with his father Mark—who has served the greater Chicago-area small business community for over 30 years—made perfect sense. Mark’s decades of experience and deep relationships now guide and mentor the next generation, ensuring every client receives seasoned judgment wrapped in genuine care.
At Lehman Accounting Group, we handle the details so you can focus on growing your business. Our core services include:
We believe accounting shouldn’t be painful or mysterious. With integrity as our foundation, we’re committed to clear communication, long-term partnerships, and making financial reporting simple and stress-free. When you work with Lehman Accounting Group, you get the technical excellence of a national firm and the personal attention of a family that truly knows and values you. We’re proud to call Chicagoland home—and even prouder to help small businesses thrive nationwide. Let’s talk about how we can make your numbers work harder for you.
For quality, solution-driven accounting services, call us at (708) 957-4800 now or request a consultation to get started.
Mark has been the trusted financial partner for Chicagoland small businesses for over three decades. A DePaul University graduate and Enrolled Agent, Mark is also a QuickBooks ProAdvisor who previously owned and operated a successful accounting practice in Lemont, Illinois.
Contractors, bars & restaurants, retail/e-commerce shops, and law firms have long counted on Mark for accurate books, painless tax filings, and practical advice that keeps more money in their pockets. One of his favorite success stories? Taking a startup restaurant from opening day to $3 million in annual revenue in just two years.
A lifelong Cubs fan and avid golfer, Mark and his wife have one grandchild (who already has a pretty good swing), and still believes the best part of this profession is watching clients turn their dreams into thriving businesses.
Now partnered with his son Jeff, Mark brings the same steady hand, straightforward talk, and genuine care that have defined his entire career.
Jeff grew up in his dad’s accounting office and always knew he’d come home to serve small businesses—just with a little Big 4 polish. After earning his degree from Marquette University and cutting his teeth at EY, Jeff spent years auditing many of the world’s largest property & casualty, life, health, and specialty insurers under GAAP, Statutory, and IFRS standards while helping large clients maintain SOX 404 internal control compliance. Jeff is an active CPA in Illinois and Wisconsin.
Today he brings that same rigor—and a lot more responsiveness—to small and mid-sized business owners who deserve elite-level tax strategy and financial clarity without the big-firm price tag or bureaucracy.
When he’s not saving clients’ money on taxes or simplifying their reporting, you’ll find Jeff on the golf course, adding to his bourbon collection, or playing guitar. Jeff is passionate about protecting and growing the livelihoods of every business owner he serves.
Together with his father Mark, Jeff is proud to carry on the family tradition at Lehman Accounting Group—only now with even sharper tools and the same hometown heart.
Nicki has been a cornerstone of the firm since 2008, when she joined William A. Lau & Co. (the practice that became Lehman Accounting Group). A University of Iowa graduate and Enrolled Agent, Nicki specializes in guiding brand-new businesses from “I have an idea” to fully operational – and tax-smart – companies. She’s helped dozens of entrepreneurs choose the right entity structure (often moving from sole proprietor to S-corporation to save thousands in self-employment taxes), register with state and federal agencies, set up payroll the right way from day one, and build bookkeeping systems that actually make sense. Clients say Nicki makes the overwhelming parts of starting and running a business feel simple and manageable.
When she’s not in the office getting to know your business (and probably your family too), Nicki loves traveling, cheering at her son’s hockey games alongside her husband, and catching the latest Bravo drama. She’s passionate about building real relationships that go far beyond the numbers – because at Lehman Accounting Group, you’re never just a client file.
Whether you’re seeking tax expertise, financial planning, or business advice, we’re here to listen and help. No pressure—just an open discussion to explore how we can work together.
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