Dependence on one client is a commercial decision

A large client can provide stability, learning and valuable revenue. It can also make the firm reluctant to negotiate, enforce scope or invest in other relationships. Concentration is therefore more than a percentage on a financial report; it changes behaviour.

Examine both revenue and capacity dependence. A client that accounts for a moderate share of revenue may consume most of a scarce specialist's attention. Losing the account and keeping it can each create different risks.

Model a plausible reduction rather than only a complete loss. What happens if the client delays renewal, halves the scope or pays later than expected? The answer can guide reserves, staffing and business development priorities.

Diversification takes time. Waiting until the relationship weakens can force the firm into hurried selling. Preserve a modest development routine while the large account is healthy, even if immediate capacity is limited.

Do not punish a good client for being important. The objective is to make your own business more resilient, not to become distant or artificially expensive. Clear scope, reliable delivery and a broader pipeline can coexist.

The useful question is whether the firm can make sound decisions without fear that one disagreement will threaten its survival. If not, concentration has begun to affect professional judgment and deserves an explicit plan.