Do Large Accounting Firm Do Merger and Acquisition Advisory Work? The Honest Answer

Yes, and the short answer to do large accounting firm do merger and acquisition advisory is that the Big 4 (Deloitte, PwC, EY, KPMG) and mid-tier firms (Grant Thornton, BDO, RSM, Baker Tilly, CohnReznick) all run substantial M&A practices. But what they actually deliver, who they serve, and what it costs varies wildly by firm size and deal size, and the wrong choice can cost a seller six figures.

Context: Why This Question Matters

Most business owners selling for the first time assume their existing CPA firm, or a brand-name firm like Deloitte or KPMG, is the natural choice to run a sale. The logic feels right: they know accounting, M&A involves accounting, therefore they should handle it. The reality is more layered. The Big 4 generated billions in transaction advisory revenue in 2025 according to the PwC US M&A Industry Trends report, but that revenue is concentrated in deals that look nothing like a $3M EBITDA HVAC company or a $15M EBITDA managed services provider.

The question matters because picking the wrong firm at the wrong deal size produces one of three bad outcomes: you pay a $400K minimum retainer for a firm that treats your deal as a B-list assignment, you get pitched advisory services the firm cannot actually deliver at your size, or you get great quality of earnings work and assume that means you also have a sell-side process running (you do not).

The Detailed Answer

Large accounting firms split M&A work into three distinct service lines, and confusing them is the single most common mistake owners make.

Transaction Services (TS). This is the largest M&A practice inside every Big 4 firm. TS teams produce Quality of Earnings (QoE) reports, run sell-side and buy-side financial due diligence, calculate working capital pegs, handle purchase price allocations under ASC 805, and structure tax-efficient deal mechanics. Deloitte’s 2025 M&A Trends Survey indicates TS engagements typically run $75K to $350K for lower middle market deals and $500K to several million for larger transactions. A TS partner is not a sell-side banker. They will not call buyers, run an auction, or negotiate price. They produce the financial evidence that supports a deal someone else is running.

Corporate Finance / M&A Advisory. This is a smaller, separate practice inside the Big 4 and mid-tier firms that does behave like an investment bank: identifying buyers, running structured processes, negotiating LOIs, and earning success fees. KPMG Corporate Finance and Deloitte Corporate Finance LLC both maintain FINRA-registered broker-dealer arms for this work. Per Refinitiv 2025 mid-market league tables, KPMG Corporate Finance ranked among the top 10 advisors by deal count globally, but the median deal was roughly $80M to $150M in enterprise value. For deals under $25M, these teams rarely take the mandate, and if they do, the engagement is usually staffed by junior bankers rather than the named partner.

Tax Structuring and Wealth Transition. Both Big 4 and mid-tier firms provide pre-sale tax planning, F-reorganization structuring, Section 1202 QSBS qualification work, installment sale modeling, and post-sale wealth transition. This is often the highest-value contribution a large accounting firm makes to a $5M to $50M deal, and it is frequently delivered alongside (not instead of) an outside sell-side advisor.

Mid-tier firms, sometimes called the “next 10,” operate differently. Grant Thornton, BDO USA, RSM US, Baker Tilly, Crowe, CohnReznick, Marcum, and Mazars all run full sell-side and buy-side M&A advisory practices that comfortably take engagements in the $5M to $500M EBITDA band. These firms compete directly with boutique investment banks for lower middle market mandates and will run a managed auction, prepare a confidential information memorandum, manage data room access, and negotiate purchase agreements. Their fee structure typically includes a $50K to $150K retainer plus a Lehman-formula or modified success fee of 1.5% to 5% of transaction value.

Regional accounting firms (Eide Bailly, Wipfli, Plante Moran, Berkowitz Pollack Brant, MorganFranklin) often have niche M&A practices focused on specific industries or geographies. Plante Moran’s M&A advisory group, for example, has built a strong industrial and manufacturing practice in the Midwest. Eide Bailly does meaningful agribusiness and dental practice work. Wipfli runs deep on construction, manufacturing, and dealership transactions. These regional firms can be a strong fit for sellers in the $10M to $100M enterprise value range who want sector expertise without Big 4 pricing, and their staffing depth on a $25M deal is often better than what a Big 4 will commit at the same fee.

Finally, several boutique investment banks trace their roots to large accounting firms even though they now operate independently. Lincoln International was founded by former Deloitte M&A bankers. Houlihan Lokey began with audit-firm connections in restructuring. Capstone Partners, Cascadia Capital, and Harris Williams all serve the lower middle market with the depth of a Big 4 process and the focus of a dedicated investment bank. For a $5M to $25M EBITDA seller, these boutiques are often the strongest fit because the deal is a priority for the firm rather than an afterthought.

How Fees Actually Compare

Pricing varies enough across firm tiers that a quick reference table helps. The figures below reflect 2025 published fee benchmarks from the Deloitte M&A Trends Survey, Capstone Partners Lower Middle Market Survey, and Axial sell-side data, with ranges adjusted for a typical $20M enterprise value transaction.

The pattern is straightforward. Above $100M enterprise value, Big 4 economics start to work for both sides. Between $25M and $100M, mid-tier accounting firms and boutique investment banks are typically the best price-to-quality fit. Below $25M, seller-paid retainers eat into proceeds, which is why buyer-paid advisor models exist for this band.

What Most Owners Get Wrong

Mistake 1: Assuming the Big 4 is the gold standard for any deal size. The Big 4 are extraordinary at deals above $250M enterprise value. Below $50M, the deal often gets handed to a manager and two analysts, the named partner appears at three meetings, and the seller pays premium pricing for non-premium attention. Capstone Partners’ 2025 Lower Middle Market Survey found that sellers in the $5M to $25M EBITDA band who hired Big 4 advisors reported lower satisfaction scores than those who hired boutique investment banks, primarily because of staffing depth and process pace.

Mistake 2: Confusing a QoE engagement with a sell-side process. A QoE report is a forensic accounting deliverable. It tells a buyer what your true, adjusted EBITDA is. It does not market your company, does not generate competing offers, and does not negotiate. Owners who hire only a Big 4 for QoE and then try to negotiate directly with one buyer leave significant value on the table, typically 15% to 30% of headline price according to Axial’s 2025 sell-side data.

Mistake 3: Treating “M&A advisor” as a single job description. When a Big 4 partner says they “do M&A,” they may mean diligence, tax structuring, valuation opinions, integration consulting, or actual sell-side banking. These are different jobs with different fee structures and different outcomes. Ask the specific question: will you run a buyer process, contact targets, and earn a success fee tied to close? If the answer is no, you still need a separate banker or M&A advisor.

How CT Acquisitions Approaches This

CT Acquisitions is a buyer-paid M&A advisor, which means sellers do not pay our fees. We focus on the under-$25M enterprise value band where Big 4 economics do not work and where mid-tier accounting firms often staff too thin. We coordinate with a seller’s existing CPA on QoE, tax structuring, and post-close wealth planning, while we run the buyer outreach, manage the LOI process, and negotiate definitive documents.

For sellers above $25M enterprise value, we frequently refer to or co-advise with mid-tier accounting M&A teams or boutique investment banks where the deal warrants it. The right answer is rarely one firm doing everything. It is a coordinated team where each provider does what they do best, and the seller does not overpay for the seat.

Related Questions

What is the difference between a Big 4 transaction services group and an investment bank?

Transaction services produces financial diligence, QoE reports, working capital calculations, and tax structuring. An investment bank runs a sale process, contacts buyers, negotiates terms, and earns a success fee at close. The two are complementary, not interchangeable. Most mid-market deals use both.

How much do Big 4 firms charge for M&A advisory?

Big 4 transaction services engagements typically run $75K to $350K for lower middle market QoE work. Big 4 corporate finance (true sell-side banking) usually requires a $200K to $500K minimum retainer plus success fees of 1% to 3% of deal value above the retainer. Per Deloitte’s 2025 fee benchmarking, the all-in cost on a $50M deal often lands between $1.2M and $2.4M.

Can a mid-tier firm like RSM or BDO actually run a sale process?

Yes. RSM, BDO, Grant Thornton, and Baker Tilly all have FINRA-registered broker-dealer affiliates and run full sell-side processes for deals in the $5M to $500M EBITDA range. Their lower middle market practices are arguably more responsive than the Big 4 because the deal economics work for the firm.

Should I use my current CPA firm to sell my business?

Probably not as the lead sell-side advisor unless your CPA firm has a dedicated M&A practice with a track record of closed deals at your size. Use them for QoE coordination, tax structuring, and ongoing accounting, but bring in a dedicated sell-side advisor or investment banker to run the buyer process. The split-role approach typically produces better outcomes.

What is a Quality of Earnings report and why do buyers require one?

A QoE is a forensic financial deliverable produced by an accounting firm that normalizes EBITDA, identifies non-recurring items, validates revenue recognition, and tests working capital. Buyers require sell-side QoE on most deals above $5M EBITDA because it accelerates their own diligence, reduces deal risk, and supports a higher offer. Per Axial 2025 data, deals with a pre-existing sell-side QoE close 28% faster and at slightly higher multiples than deals without one.

What to Do Next

If you are an owner in the $5M to $25M enterprise value band trying to figure out which type of firm to hire, the cheapest move is a short conversation that maps your specific situation to the right service mix. Most sellers end up with a combination: a sell-side advisor running the process, a QoE provider (often a mid-tier accounting firm), and a tax/wealth planner. We can help you scope what you actually need and what you do not.

Related reading: our guide to Quality of Earnings reports, our breakdown of M&A advisor fees, and our step-by-step sell-side process guide.