If you’re googling this, you’re probably staring at a live deal and thinking something like:

“I know I should do proper due diligence… but are we talking $5k, $50k, or $500k?”

Totally fair question. Due diligence is one of those things people talk about like it’s obvious, but very few founders or deal teams ever see a clean, honest breakdown of what it actually costs and what drives those numbers.

This guide is my attempt to give you that: real ranges, what changes the price, and where you can save money without being reckless.

The Quick Answer: Typical Cost Ranges in 2025

Let’s start with some anchors.

Across M&A deals, independent benchmarks and industry guides put total external due diligence costs (financial, legal, tax, tech, etc.) at roughly:

0.2%–4% of deal value overall, depending on complexity and region
Within broader M&A fees, due diligence alone often lands around 0.5%–2% of deal value, with the rest going to investment bankers, lawyers, and financing costs

For a simple way to think about it:

Small deals (< $10M): Roughly $25k–$75k in total third-party due diligence
Mid-sized deals ($10M–$100M): Often $50k–$200k
Large deals ($100M+): Commonly $150k–$500k+, especially if multiple geographies and workstreams are involved

Now let's unpack what's actually inside those numbers.

What Drives Due Diligence Cost?

Most of the variance comes down to a few levers:

Deal size & complexity – more entities, countries, products, and data = more work.
Scope – are you doing only basic financial checks, or full financial + legal + tax + tech + cyber + HR?
Provider type – Big 4 / global firms vs boutiques and specialists.
Timeline – “we need this in 10 days” pricing is different from “we have 6–8 weeks.”
Data quality & organization – messy or incomplete records = more billable hours.

You have more control over these than it feels like in the heat of a deal. Peony provides AI-native data rooms with instant Q&A and question analytics to reduce due diligence costs by streamlining the process.

Cost Breakdown by Due Diligence Workstream

1. Financial Due Diligence & Quality of Earnings

For small business acquisitions, a basic financial review (sanity-checking historicals, normalizing EBITDA, and checking working capital) typically runs:

$2k–$5k for very light “verification-style” reviews on small deals

A full quality of earnings (QoE) report is where the serious work (and cost) starts:

$10k–$30k for smaller or simpler businesses
$25k–$35k is a common band quoted for small businesses under ~$10M revenue
$60k–$100k+ is common for larger, more complex companies, and some deals go into six figures for deep, multi-entity QoE work

For most serious M&A processes, financial/QoE is usually one of the top two line items.

2. Legal Due Diligence

Legal DD costs scale hard with complexity: number of contracts, jurisdictions, and issues.

For small business acquisitions, some advisors give this kind of ballpark:

Around $5k for focused legal due diligence in a smaller, mostly domestic deal

For mid-sized and larger deals, it’s more often hourly, not fixed, but you’ll commonly see:

Low five figures for fairly standard private deals
Mid to high five figures (or more) for multi-jurisdictional or heavily regulated targets

Remember: legal DD often blends into SPA drafting and negotiation, which adds another chunk of fees. Secure document sharing platforms provide identity-bound access and watermarking for secure legal document sharing.

3. Tax Due Diligence

Tax DD costs depend on group structure, cross-border footprint, and whether you’re in a Pillar Two / BEPS 2.0 regime.

Typical ranges for a standalone tax due diligence workstream:

$10k–$30k for relatively simple, single-jurisdiction deals
$30k–$75k+ when you’re looking at multi-entity, multi-country structures or complex issues (transfer pricing, NOLs, global minimum tax, etc.)

If there's heavy international tax planning in the target, assume the higher end or above.

4. Technology / IT Due Diligence

This has become non-negotiable for most software and tech-enabled deals.

Recent guides and providers quote:

$5k–$25k in the US for software/tech DD, depending on scope and depth
In the UK, more comprehensive software technical DD often lands between £20k and £100k, with large enterprise audits going over £150k

If the target's tech stack is the heart of the deal, this is not where you want to cheap out. Peony provides secure data rooms with screenshot protection and password protection for secure technical documentation sharing.

5. Cybersecurity Due Diligence

You’ll see a huge spread here:

Some vendors advertise cyber due diligence packages at $2k–$5k
More thorough engagements (with system access, testing, regulatory mapping, and post-deal planning) often move into the $10k–$30k+ range, especially on larger or regulated deals

Cheap, questionnaire-only cyber DD can be better than nothing, but many experts point out that incomplete cyber checks can end up being far more expensive in breach costs later.

6. Commercial / Market Due Diligence

Commercial DD (market size, competitive landscape, customer interviews, pricing, etc.) is highly variable:

$20k–$50k for focused, desk-research-heavy projects
$50k–$150k+ when you’re using top-tier consultancies or doing wide customer/partner interview programs

For growth PE and later-stage VC, commercial DD is often one of the biggest single components after legal and QoE.

7. Vendor / Third-Party Due Diligence

Sometimes you’re not buying a company, you’re vetting a critical vendor (payments, cloud, core system).

Standalone vendor due diligence reviews can range from:

As low as $200–$400 for simple, standardized assessments
Up to $15k–$20k for deep, custom reviews of high-risk third parties

Many organizations now use TPRM platforms on subscription, so the per-vendor marginal cost is essentially your internal time + any add-on expert reviews.

8. Real Estate Due Diligence

For property-heavy deals, you’ll layer on:

Property inspections, surveys, environmental assessments (Phase I ESA, sometimes PRA climate resilience assessments), and title work

These are often priced per property, ranging from a few thousand dollars for basic inspections and Phase I work to five figures per site for more complex environmental or resilience studies.

Hidden Costs Founders Constantly Underestimate

Beyond third-party invoices, there are a few “soft” costs you should factor in:

Internal time – your finance lead, CTO, and legal counsel might each lose weeks answering questions and pulling data.
Deal fatigue – poorly scoped DD that drags on can kill momentum and bargaining power.
Re-work – disorganized data rooms force advisers to redo analyses when new files appear late.

These don't show up on an invoice, but you absolutely pay for them.

How to Reduce Due Diligence Costs Without Cutting Corners

Three levers actually work in practice:

Scope ruthlessly by risk Not every deal needs every workstream at “Big 4 for 8 weeks” depth. Small domestic deals might need only targeted financial, legal, and basic tech/cyber; huge cross-border carve-outs justify full-scope everything.
Invest in a clean data room early Well-structured virtual data rooms and standardized document lists can reduce adviser time (and cost) significantly; some providers estimate tech-enabled processes can cut due diligence costs by 25–35% by avoiding redundant work and clarifying scope. Peony provides AI-native data rooms with instant Q&A and question analytics to reduce costs by streamlining the process.
Use specialists, not just big brands For technical, cyber, or niche regulatory areas, focused boutiques often deliver better value than generalist teams, especially on mid-market deals.

If you walk away with one mental model, let it be this:

Due diligence is insurance plus x-ray. You're not paying for documents; you're paying to avoid surprises that are bigger than the fee.

Once you frame it that way, the question shifts from "How little can I spend?" to "What's the smart amount to spend to protect this investment?" – and that's where good decisions start. Use Peony for secure due diligence data rooms with AI-native Q&A, question analytics, and secure sharing to reduce costs and accelerate the process.

FAQ: Due Diligence Costs in 2025

Is there a “too much” number for due diligence? If you’re consistently spending >3–4% of deal value on DD for straightforward, competitive transactions, you may be over-engineering. But on complex, high-risk deals, that level can be rational if it materially derisks a large check.

Who usually pays for due diligence—the buyer or seller? In classic buy-side M&A, the buyer pays for their own advisors. In sell-side or auction processes, the seller might commission vendor DD (e.g., QoE) and share it with bidders, effectively front-loading some of the cost.

Can I skip certain workstreams to save money? You can deepen or lighten each stream, but skipping financial, legal, or at least basic tech/cyber altogether is usually a false economy. If the deal is too small to justify any diligence spend, ask whether it’s big enough to matter at all.

How early should I budget for due diligence? As soon as you're seriously considering a transaction. Treat DD as part of deal economics, not an afterthought. A simple rule: the moment you think in terms of "term sheet," you should also think in terms of "DD budget."

How much does due diligence cost?

Due diligence typically costs 0.2%–4% of deal value, with small deals ($25k–$75k), mid-sized deals ($50k–$200k), and large deals ($150k–$500k+). Peony provides AI-native data rooms with instant Q&A and question analytics to reduce costs by 25–35% by streamlining the process.

How do you reduce due diligence costs?

Scope ruthlessly by risk, invest in a clean data room early, and use specialists. Peony helps: upload all documents to a secure data room with AI-native Q&A so stakeholders self-serve 80–90% of questions, reducing adviser time and costs.

What's the best data room to reduce due diligence costs?

Peony is best: upload all diligence materials to a secure AI-native data room with instant Q&A, question analytics, identity-bound access, password protection, and watermarking to reduce costs by 25–35% and accelerate the process.

Can you see what questions stakeholders ask during due diligence?

Most traditional data rooms only show page views. Peony provides complete question analytics: see what stakeholders ask most, which topics cause confusion, and areas that stall deals for proactive follow-ups and cost reduction.

How do you share materials securely during due diligence?

Peony is best: upload all diligence materials to a secure Peony room with identity-bound access, password protection, watermarking, and tracking, then share one protected link instead of email attachments or Google Drive links.

Streamline Due Diligence

Due Diligence Cost Breakdown in 2025: Complete Pricing Guide for M&A & Investment