You bill by the project, not the paycheck. We handle the entity structure, quarterly taxes, and deductions that come with project-based income — so you can focus on the design and the build.
Engineers and architects face a tax picture most generalist preparers don't fully understand: project-based income that arrives in lump sums instead of even paychecks, a mix of W-2 employment and 1099 consulting for many practitioners, home office setups for remote design work, and an entity decision that affects every dollar of self-employment tax you pay.
At Mercer Flanagan, we've worked with engineers, architects, and design professionals in Frederick and surrounding counties for over 50 years. We know how project timing affects your tax bill. We know the deductions specific to your field. And we're here year-round — not just in April.
"The engineers and architects who come to us mid-year usually have the same issue: a big project closed, the income landed all at once, and their quarterly estimates were calculated for a completely different year. That's an avoidable problem with the right planning."
We work with:
These are the situations we hear about most often from new clients in engineering and architecture.
Project-based income rarely arrives evenly across the year. An estimate calculated in January based on last year's numbers can leave you badly under- or over-paid by Q4 once a major project closes. We recalculate as the year actually unfolds.
Many solo and small-firm engineers and architects are still operating as a sole proprietor or a standard LLC well past the point where an S-Corp election would meaningfully reduce self-employment tax. This is one of the first things we evaluate for every new client.
Many engineers and architects work a W-2 job while taking on consulting, design, or contract work on the side. These two income streams need to be coordinated on one return, not treated as separate problems.
Dedicated home design space, CAD and modeling software, professional licensing, and continuing education are routinely underclaimed or miscalculated by generalist preparers who don't see these deductions often.
Travel between job sites, client meetings, and inspections adds up — but only if it's tracked properly throughout the year rather than estimated after the fact.
If you run your own practice, clean bookkeeping is the foundation of accurate returns and the ability to see whether individual projects are actually profitable. We provide monthly bookkeeping and QuickBooks support for firms that need it.
How your practice is legally structured has a bigger impact on your tax bill than almost any other single decision. Here's how the common structures compare for engineers and architects.
| Structure | Self-Employment Tax | Admin Complexity | Best For |
|---|---|---|---|
| Sole Proprietor / Single-Member LLC | 15.3% on all net income | Lowest | Early-stage or part-time practitioners |
| S-Corporation | Only on reasonable salary | Moderate | Established engineers & architects earning $80K+ net |
| Professional Corporation / PLLC | Varies by election | Moderate–High | Required in some states for licensed engineers/architects |
| Partnership / Multi-Member LLC | Can be high | High | Small firms with multiple principal owners |
The right answer depends on your income level, whether you have employees, and your state licensing requirements. We analyze this for every new client. Read our S-Corp vs. LLC guide →
We evaluate your current structure, run the numbers on what an S-Corp election would save you, and handle the paperwork to make the switch if it makes sense. For many engineers and architects earning over $80,000 in net practice income, this is the highest-return tax move available.
S-Corp vs. LLC: Which Is Right for You? →We prepare your firm's business return — Schedule C, Form 1120-S for S-Corps, or Form 1065 for partnerships — along with your personal Form 1040, including all schedule attachments. Everything is handled under one roof with full context across both returns.
Small Business Tax Services → Individual Tax Preparation →We calculate your quarterly estimated payments based on your actual project pipeline and adjust as projects close throughout the year. No surprise April bills. No unnecessary overpayments sitting with the IRS for months.
Tax Planning Services →Dedicated home design space, CAD and modeling software, drafting equipment, and professional licensing are all deductible when documented correctly. We make sure these are captured and substantiated in a way that holds up if questioned.
Mileage between job sites, inspections, and client meetings adds up over a year. We help you set up a tracking system so this deduction is fully captured rather than estimated at tax time.
If you run your own practice, your books need to be clean, current, and organized — not just for tax purposes but so you can see which projects and clients are actually profitable. We offer ongoing monthly bookkeeping using QuickBooks and can clean up the books if they've fallen behind.
QuickBooks Support & Training →If your firm needs compiled financial statements for a bank loan, bonding requirement, or partner buy-in agreement, we handle that. Clean, professionally prepared statements that lenders and partners accept.
Financial Statement Compilations →For firm owners who want more than tax prep — we offer fractional CFO support including project profitability analysis, overhead benchmarking, and strategic planning guidance. You get a senior financial advisor without the cost of a full-time hire.
Fractional CFO Services →These are the deductions that are specific to engineering and architecture professionals — the ones generalist preparers most often underutilize or miss entirely. Every situation is different, and eligibility depends on your specific circumstances, but these are worth discussing with us.
Deductibility always depends on your specific facts and circumstances. The IRS has specific rules about what qualifies, how to document it, and how to calculate it. We make sure you're capturing what you're entitled to — and that it's documented properly so it holds up if questioned.
Big firms want big corporate clients. We built our practice around the engineers, architects, and professionals who are the backbone of Frederick County. You won't be handed off to a junior associate. You won't wait three weeks for a call back. You get a CPA who knows your name and your situation.
Year Mercer Flanagan was founded in Frederick, MD
Years serving local professionals, businesses & nonprofits
Rated by clients across Frederick County
Access to your CPA — not just during tax season
Year-round access to your CPA. Questions get answered when you have them, not weeks later.
We understand how uneven project timing affects your tax planning.
We're based in Frederick, MD. We know this community and we're not going anywhere.
We don't just file your returns. We contact you when something changes that affects your tax situation.
Book a free 20-minute consultation. We'll tell you honestly whether we can help — and what it would cost. No pressure, no obligation.
Book a Free Consultation