A large customer can be an important source of stability and growth. It can also make the business sensitive to changes in one relationship.
Revenue concentration is a starting measure of that dependence. It does not, by itself, tell you whether an account is healthy or whether a particular percentage is acceptable.
Use a consistent denominator
For a defined period, divide a customer's revenue by total company revenue from the same period. In an illustrative business with $40,000 from one customer and $100,000 of total revenue, that customer's share is 40%.
Review the largest account and the combined share of several major accounts. Document whether linked companies belong to one economic relationship so the presentation does not hide dependence across separate names.
Look beyond the percentage
Consider payment timing, contract duration, renewal conditions, margins and delivery commitments. Revenue dependence can differ from cash dependence or operational dependence.
Ask what would change if an important account reduced work or paid later. Use scenarios grounded in your own commitments rather than treating a hypothetical event as a prediction.
Choose a proportionate response
Responses might include improving relationship coverage, clarifying renewal expectations, diversifying qualified opportunities or reviewing the timing of expenses. The appropriate choice depends on the business and its resources.
There is no universal safe threshold in this exercise. A concentration measure should open a discussion about resilience, not trigger an automatic decision to reject a valuable customer.