What are VC due diligence customer calls?

Customer calls are conversations in which a venture capital investor (VC) speaks directly with your customers during due diligence. Due diligence is the detailed check an investor runs on your company before investing. If you run a B2B company, a company that sells to other businesses, VCs will at some point ask to speak to your customers.

These calls are short. About 30 minutes between a VC and one of your customers can strengthen or damage your round. Handled well, they reinforce your story and help investors build conviction. Handled poorly, they create confusion or new doubts.

Preparation often starts only after due diligence has begun, and sometimes not at all. The usual assumption sounds like this: "Our customers love us. What could go wrong?" I wrote about this risk in Customer Reference Calls.

Why can a happy customer still hurt your round?

Because customers are not trained in investor conversations. They do not know what VCs listen for. They know your product from the side of a user and a buyer, and they rarely see your round from the side of an investor. A customer may say something that makes sense from their own perspective, and the investor may read it very differently.

The call also affects your customer. You do not want them to hang up and wonder: "Wait… are they running out of money?" So you need a balance between confidence and transparency, without causing concern or confusion on either side. That balance is hard to improvise. It needs preparation:

• Select the right customers.
• Brief them properly.
• Explain why they are being asked.
• Prepare them so the call does not surprise them.
• Coordinate the requests, so that six VCs do not call the same two people in the same week.

Which customers should an investor speak to?

Only customers you have chosen and aligned with first. Do not let VCs approach your customers without your OK. It is fair to insist on this.

One of the riskiest moves is an open list. A founder sends investors a spreadsheet with 20 customers and the note: "Reach out to whoever you want." It feels transparent. In practice, you hand a critical part of your round to someone else.

For the selection itself, three questions help:

1. Who loves the product?
2. Who speaks fluent English?
3. Who understands your company as it is today? A customer who still describes what you did two pivots ago tells an outdated story. A pivot is a major change in a startup's direction.

How do you ask a customer to take a reference call?

Frame the request around your progress and your relationship with the customer. Avoid the plain version: "Hey, we're trying to raise money. Can you talk to this investor?"

A better framing: tell them that top-tier investors are excited about your traction. Make them feel part of the company's path. This builds emotional commitment.

The framing also protects you from the question "are they running out of money?". Talking about investor excitement keeps the focus on your traction. A request framed as "we need money" can raise exactly that question.

Then prepare your champions, the customers who will speak for you:

• Send a short FAQ: what the call is, why it matters and what to expect.
• Remind them of your vision: your current vision and positioning, so they describe today's company.
• Skip the script: no prepared answers. The goal is that they feel ready.

What should you do after a reference call?

Follow up with both sides: the investor and the customer.

1. Ask the VC how the call went: it shows that you care and gives you a chance to clear up confusion before it spreads.
2. Thank the customer: check in, appreciate their time, and perhaps send a small gift. It strengthens the relationship and makes them more likely to help again.

Seen this way, reference calls are also a chance to activate your strongest supporters among your customers.

How do you coordinate reference calls with several investors?

Treat the calls as one planned sequence across all investors in due diligence. If several funds check your company at the same time, the same few customers can receive call after call. Six VCs calling the same two people in the same week is the situation to prevent.

• Keep one overview: which investor speaks to which customer, and when.
• Tell each customer in advance: who will call, from which fund and what the call is about.
• Use your aligned group: route every request to customers you have selected and briefed.
• Follow up after each call: with the investor and with the customer, before the next call takes place.

Coordination also protects the relationship with your customers. A customer who is prepared before the call and thanked afterwards is more likely to help again.

What does the full process look like?

Six steps cover the process from selection to thank-you. They are described in How to master customer reference calls:

1. Choose who they speak to: investors only call customers you have aligned with.
2. Select the right customers: they love the product, speak fluent English and understand your company today.
3. Frame the ask thoughtfully: lead with investor excitement about your traction.
4. Prep your champions: a short FAQ and a reminder of your vision and positioning.
5. Follow up with the VC: ask how the call went.
6. Thank your customers: appreciate their time.

If you start these steps before due diligence begins, your customers are already chosen and briefed when the first investor asks.