What Happens if My Business Relies Heavily on One Customer?

Why buyers care about customer concentration

When a buyer values your business, they’re really buying your future earnings, not just your past results. If one customer accounts for a large share of your revenue, a buyer has to ask: what happens to this business if that customer leaves, cuts back, or renegotiates pricing after the sale? The more revenue tied to one relationship, the more the buyer’s own investment depends on something they don’t control.

This is sometimes called customer concentration risk, and it’s one of the most common concerns buyers raise during due diligence for service businesses, since service businesses often build relationships around a small number of accounts.

How much revenue from one customer is considered a problem?

There’s no single, agreed-upon percentage that defines a problem. Public data on an exact threshold is limited, and estimates vary widely depending on the industry, the source, and the buyer. As a general pattern, buyers tend to grow more cautious as a single customer’s share of revenue increases, and concern typically increases further when a handful of customers together make up most of your business. Rather than focusing on a specific number, it’s more useful to understand the general pattern: the more revenue riding on fewer relationships, the more risk a buyer perceives, and the more that risk shows up in price or deal terms.

How does customer concentration affect the deal structure, not just the price?

Customer concentration rarely makes a business impossible to sell, but it commonly affects the deal in a few ways:

• Lower offers. Buyers may adjust their offer downward to reflect the added risk.
• More scrutiny during due diligence. Expect detailed questions about the customer relationship, contract terms, and how long it’s been in place.
• Deal structure changes. Instead of paying the full price in cash at closing, a buyer may ask for an earn-out, where part of the price depends on the business (and that customer relationship) continuing to perform after the sale.
• A narrower buyer pool. Some buyers, particularly those relying on financing, may be more cautious about concentrated businesses, while others may see the same relationship as an opportunity if they believe they can maintain or grow it.

What can I do to reduce this risk before selling?

If a large share of your revenue comes from one or a few customers, there are practical steps that may ease a buyer’s concerns:

• Long-term contracts. A signed multi-year agreement with the customer gives a buyer more confidence the relationship will continue.
• Diversifying your customer base. Actively growing other accounts, even modestly, shows a trend in the right direction rather than a static risk.
• Documenting the relationship. Show how the relationship is managed, who else on your team is involved, and what would happen if you personally stepped back.
• Being transparent early. Buyers generally respond better to a concentration issue raised upfront with a clear explanation than one discovered later during due diligence.

What can change how much this matters

The impact of customer concentration depends on your industry, how replaceable that revenue would be, how long the relationship has lasted, and whether a formal contract protects it. A concentrated business isn’t automatically a red flag if the relationship is stable, contractual, and well documented. It becomes more of a concern when the relationship is informal, personal, or easily lost.

A practical next step

A useful first step is calculating what percentage of your revenue comes from your largest customer and your top five customers combined. Bringing this information to a broker or valuation professional early lets them help you understand how it may affect your specific situation, and what steps might be worth taking before you go to market.