St. Charles CPAs for Small Business and Contractors

St. Charles County has grown into one of the most active small business markets in greater St. Louis. Trades and contractors, retail and restaurants along Main Street, professional services up and down Highway 70, and a steady mix of young families and retirees. The CPA work has to match that range.

Thompson Flaherty is an Illinois and Missouri-licensed CPA firm. We work with St. Charles County small business owners and families who want a year-round CPA relationship. To start that conversation, get in touch with our team.

St. Charles County Areas We Serve

St. Charles, St. Peters, O’Fallon, Cottleville, Weldon Spring, Wentzville, and the rural areas in between. Most engagements are virtual, but we will meet in person when the situation calls for it.

What a St. Charles CPA Costs

Pricing in St. Charles County is consistent with the broader St. Louis metro. Tax return only (S-corp or LLC) runs roughly $1,200 to $3,000. Monthly bookkeeping is typically $400 to $1,500 a month. A year-round CPA engagement with bookkeeping, strategy, and quarterly check-ins lands most clients between $1,200 and $3,000 a month, all-in. We quote real numbers after a 30-minute intro call.

Missouri Tax Issues St. Charles Owners Run Into Most

Missouri’s flat-rate personal income tax (4.7% in 2024, adjusted annually) sounds simple, but St. Charles contractors and trades businesses run into the bigger issues: state-level sales tax compliance on materials, the Missouri PTE election when the federal SALT cap is in play, and the W-2 vs 1099 worker classification rules that Missouri labor enforces aggressively. We work the Missouri Department of Revenue and Department of Labor rules into every engagement.

When Should a St. Charles Business Switch to an S-Corp?

When net business profit is comfortably above a reasonable W-2 salary for the work, the S-corp election starts saving self-employment tax. For most St. Charles single-owner businesses, that line is somewhere between $60,000 and $80,000 of net profit. The math is sensitive to the industry, the owner’s other income, and Missouri-side considerations like the PTE election. We walk through it on our business tax services page.

Industries We Work With in St. Charles

Trades and contractors, independent restaurants and retail, healthcare and dental practices, professional services, and small manufacturing. Generalist firm by design, which means you work with one CPA who knows the whole picture.

How to Start

Schedule a 30-minute intro call through our contact page. No cost, no pressure, and we will tell you honestly whether Thompson Flaherty is the right fit.

Related St. Louis Pages

St. Louis CPA: see /cpa-st-louis/. University City CPA: see /cpa-university-city/.