Vendor Due Diligence: When the Seller Checks First

A vendor due diligence is a due diligence that the seller commissions himself before any buyer examines his company at all.

A due diligence support set up early makes the seller's review robust and controllable.

How a sale process runs in full and how we support it is described under Selling a company.

At first this sounds paradoxical: why should one have one's own company examined thoroughly? Because that is exactly what strengthens the negotiating position, can speed up the process and clears bad surprises out of the way before they turn into a price reduction.

What is a vendor due diligence?

A vendor due diligence (VDD) is a review of one's own company that the seller has carried out by an independent advisor before the sales process and whose result he makes available to prospective buyers. According to Rödl & Partner's account, it covers the legal, tax and financial situation including an assessment of risks; alternatively the seller limits himself to a purely descriptive fact book. The buyer thereby gets a neutral picture early, but as a rule it does not replace his own review.

The difference from a classic due diligence

In the usual due diligence, the buyer examines the target company before buying. In a VDD this is reversed: the seller commissions an independent advisor to examine his own company, and presents the result, the VDD report, to interested parties.

The buyer thereby receives a neutral, robust picture early. This does not fully replace his own review, but it can shorten it.

What a vendor due diligence achieves

The benefit lies in four points. First, control: the seller learns of weaknesses first and can remedy or explain them before a buyer uses them as leverage. Second, speed: a finished report can accelerate the buyer's review. Third, competition: several interested parties can review in parallel on the same basis instead of one after another. Fourth, credibility: an independent report creates trust and takes the edge out of discussions.

In short: the VDD shifts part of the power of interpretation from the buyer to the seller.

Report or fact book: which form fits?

Not every VDD is equally deep. Two forms are usual.

Feature	VDD report	Fact book
Content	review with assessment of findings and risks	descriptive presentation of figures and facts
Areas	mostly finance, tax, legal, commercial depending on the case	mostly finance, often without risk assessment
Effort	higher	lower
Informative value for buyers	higher	lower, but quicker to prepare

The costs depend on scope and size. There are no robust, publicly collected cost figures for this; we therefore state none. Obtain two to three offers for the desired scope and have the scope of services described in writing.

Reliance letter: who is liable to the buyer?

The VDD report is prepared for the seller. Whether a buyer or his financing bank may rely on the content is regulated by a separate document. According to Rödl & Partner there are two ways: with a non-reliance letter, the seller's advisors do not want to be liable to buyer and banks for the content. With a reliance letter, liability is regulated via the scope of engagement, a reference date for the statements and agreed liability caps.

A publication by Lenz & Staehelin describes the practice as follows: VDD reports are often first made available to interested parties on a non-reliance basis, and the successful bidder can then receive a reliance letter. Reliance letters almost always contain a maximum liability amount for the report's author, where the level of the fee, and not the transaction volume, determines the limit. The interests are also particular: the author of the report is the seller's advisor, but the interests of seller and buyer run against each other.

For you as the seller this means: clarify already at the time of engagement whether and for whom a reliance letter is envisaged. That affects scope, reference date and fee.

Disclosure and purchase agreement

A VDD report discloses facts. The law knows the principle that a buyer who knows of a defect at the time of the contract in principle loses his rights from it (§ 442 Abs. 1 BGB); this does not apply if the seller fraudulently concealed the defect or gave a guarantee. And a seller cannot rely on an agreed exclusion of liability to the extent that he fraudulently concealed a defect (§ 444 BGB). How disclosure, warranties and liability limits interact in the purchase agreement should therefore be regulated expressly and coordinated with your lawyer. This is a classification, not legal advice.

When a vendor due diligence is worthwhile

Not every sale needs a VDD. It is worthwhile above all for larger, more complex transactions, for a bidding process with several interested parties and when the company has topics that one would rather explain oneself than have discovered by the buyer.

Five questions help with the decision:

1. Are there likely to be several interested parties reviewing in parallel?
2. Are there topics that you would rather classify yourself (customer concentration, tax questions, open contracts)?
3. Is your bookkeeping set up so that a reviewer can work quickly?
4. Is the effort in reasonable proportion to the expected purchase price?
5. Do you have time for a lead time before the start of the buyer approach?

On the order of magnitude: previous owners who aim for a sale in the KfW Succession Monitor Mittelstand 2025 cite a targeted sale price of on average around EUR 499,000, the median is EUR 375,000. With such amounts and only one interested party, a comprehensive VDD is often out of proportion to the benefit; a fact book or a well-organised own preparation can suffice. How a sale works in principle is shown by the process of a company sale. A first indication of which price range is in play is given by the company value calculator.

How it works

An independent advisor, usually an audit firm or M&A advisory, examines finance, tax, legal and, depending on the case, commercial topics. The result is a structured VDD report or a fact book and often a prepared data room. These documents form the basis on which interested parties review. A ready-made structure for this data room is provided by the data room index with 83 documents of the M&A Data Room Manager. How long this takes depends on the scope; we have no robust average values.

The limits

A VDD is not a free pass. It costs money and lead time, and most buyers additionally carry out a confirmatory review (confirmatory due diligence) before they sign. Its value lies not in replacing the buyer's review, but in steering the process and strengthening the seller's negotiating position. A report that names weaknesses objectively is more credible than one that leaves them out.

Vendor due diligence, red flag report, disclosure: the terms of the review phase are briefly defined in the glossary.

A company sale is the most important transaction of an entrepreneur's life. Get independent and discreet support: IGCP Capital Partners. → igcp.at

Preparation is particularly worthwhile in regulated industries, for example in medical technology, where the technical documentation decides price and pace.

For the data room a short memo on the new topics of 2027 is worthwhile; the article on review items for sellers sets out what they are.

Frequently asked questions

What is a vendor due diligence?

A due diligence that the seller commissions himself before the sale. An independent advisor examines the company and prepares a report that prospective buyers receive. The buyer thereby gets a neutral picture early, and the seller retains control of the process.

What is the difference from a normal due diligence?

In a normal due diligence, the buyer examines the target company. In a vendor due diligence, the seller examines his own company in advance and discloses the result. Both can occur in one process: first the seller's VDD, then a confirmatory review by the buyer.

For whom is a vendor due diligence worthwhile?

Above all for larger, complex transactions and for bidding processes with several interested parties. In small sales with only one interested party, the effort often exceeds the benefit. Whether it makes sense depends on size, complexity and type of process.

Does the vendor due diligence replace the buyer's review?

As a rule not fully. Most buyers carry out a confirmatory due diligence before signing. The VDD, however, shortens and structures it and shifts part of the power of interpretation to the seller.

What is a reliance letter?

A reliance letter allows a third party, for example the buyer or his bank, to rely on a due diligence report that someone else commissioned. It regulates the scope and limits of this reliance, usually with a maximum liability amount and a reference date.

What does a vendor due diligence cost?

That depends on the scope. There are no publicly documented average values, so we state no figure. Obtain several offers for the desired scope.

The vendor due diligence is one building block of a larger preparation. The framework for this is described in Exit preparation.

Sources, retrieved on 29.09.2026: Rödl & Partner, Vendor Due Diligence: Vorteile einer Prüfung des eigenen Unternehmens (roedl.com, 7 July 2021); Lenz & Staehelin, Reliance Letters (lenzstaehelin.com); § 442 BGB, § 444 BGB (lxgesetze.de); KfW Research, Nachfolge-Monitoring Mittelstand 2025 (kfw.de, Fokus Volkswirtschaft Nr. 526, 9 January 2026). Classification, not legal advice.