My Business Depends Heavily on One Customer — How Risky Is That?

Relying heavily on one customer — commonly described as customer concentration risk — means the business's financial health is tied to a single relationship staying intact, on similar terms, indefinitely. The more revenue that sits with one customer, the more exposed the entire business is to a decision that customer makes, for reasons that may have nothing to do with your performance.

A large, reliable customer feels like the opposite of risk — it's stable, predictable, and often genuinely pleasant to work with. But stability from the customer's side doesn't protect you from their business being sold, their strategy changing, a new decision-maker preferring a different supplier, or their own financial trouble — none of which you control, and none of which shows up as a warning sign in your own numbers until it happens.

The following is an illustrative screening guide, not a regulatory or industry-standard benchmark — there's no officially defined “safe” percentage, and appropriate thresholds genuinely vary by business and industry. It's offered as a rough starting point for your own thinking, not an authoritative scale.

There's no universally “safe” threshold — context matters, including how replaceable that revenue would genuinely be, and how much notice you'd realistically get if the relationship ended. But the higher the percentage, the more deliberately this risk deserves managing, rather than simply being enjoyed while it lasts.

• Cash flow — a single large customer paying late, or the loss of the relationship entirely, can create an outsized cash-flow shock relative to a more diversified customer base.

• Negotiating power — a dominant customer often knows they're dominant, which can quietly erode your pricing and terms over time.

• Business valuation — if you ever plan to sell the business, heavy customer concentration is one of the first things a buyer will flag as a risk, and it can meaningfully reduce what they're willing to pay.

• Strategic flexibility — decisions across the whole business can end up shaped disproportionately around retaining one customer's preferences, rather than the business's own broader direction.

• Actively pursue diversification, deliberately, not just opportunistically. Set a genuine goal for reducing the percentage over time, rather than hoping new customers arrive on their own.

• Strengthen the relationship's foundations. Formal contracts, clear terms, and multiple points of contact within the customer's organisation reduce the risk of losing everything if one relationship or decision-maker changes.

• Build a genuine cash reserve sized around this specific risk. If concentration is high, your reserve target, covered in its own guide, should reasonably be higher than a more diversified business would need.

• Understand the early warning signs. Slower payment, reduced order volume, or a change in the customer's own business are all worth taking seriously, early, rather than after the relationship has already ended.

• What percentage of my total revenue currently comes from my single largest customer?

• If that relationship ended tomorrow, could the business genuinely survive the transition?

• Do I have a deliberate plan to diversify, or am I simply hoping new customers arrive?

• Is my cash reserve sized appropriately for this specific risk?

• you want to understand your genuine financial exposure to a key customer relationship;

• you're planning to reduce concentration and want a realistic diversification strategy;

• you're preparing to sell the business and want concentration risk addressed before it affects valuation; or

• you want your cash reserve and forecasting adjusted to reflect this specific risk properly.

→ How Much Cash Should My Business Keep in Reserve?

→ Which Products, Services or Customers Are Actually Making Me Money?

→ How Is a Small Business Valued — and What Actually Makes It More Valuable?

SKC Accounting | Knowledge Centre | Knowledge Guide 090

Last reviewed: August 2026

General information only. This guide does not take into account your individual circumstances and is not a substitute for professional accounting, taxation, legal or financial advice.